K(+)
362,296 routes · scope human · up to 3 steps · built 5 October 2026 · Reactions · API
458 compounds within 3 steps: 5 in 1, 61 in 2, 392 in 3
Three steps
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- oxaloacetate + L-alanine = L-aspartate + pyruvate
- L-selenocysteine selenide-lyase (L-alanine-forming)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + L-methionine(out) = L-aspartate(out) + L-methionine(in)
- L-Methionine:tRNAMet ligase (AMP-forming)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- (S)-lactate + NAD(+) = pyruvate + NADH + H(+)
Catalysed by SLC1A1, CTH, LDHA, LDHB and 3 moreinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- transport of 3-sulfinoalanine and aspartate (cytosol to mitochondria)
- 3-sulfino-L-alanine carboxy-lyase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 5 moreinner side of the membrane, outer side of the membrane, mitochondrial matrix, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + sulfate(out) = L-aspartate(out) + sulfate(in)
- Transport of Quinolinic Acid
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 4 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosolOne of 2 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + L-methionine(out) = L-aspartate(out) + L-methionine(in)
- glyoxylate + L-methionine = 4-methylsulfanyl-2-oxobutanoate + glycine
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + L-phenylalanine(out) = L-aspartate(out) + L-phenylalanine(in)
- (S)-lactate + L-phenylalanine = N-[(S)-lactoyl]-L-phenylalanine + H2O
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- 2-oxobutanoate + L-alanine = (2S)-2-aminobutanoate + pyruvate
Catalysed by SLC1A1, CTH, AGXT2inner side of the membrane, outer side of the membrane, cytosolOne of 2 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-tryptophan(out) + L-aspartate(in) = L-tryptophan(in) + L-aspartate(out)
- L-tryptophan decarboxy-lyase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + L-glutamine(out) = L-aspartate(out) + L-glutamine(in)
- L-Glutamine:pyruvate aminotransferase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, cytosolOne of 5 routes
- serotonin(out) + K(+)(in) + Na(+)(out) + H(+)(in) = serotonin(in) + K(+)(out) + Na(+)(in) + H(+)(out)
- acetyl-CoA:aralkylamine N-acetyltransferase
- S-adenosyl-L-homocysteine:N-acetylserotonin O-methyltransferase
Catalysed by SLC6A4, AANAT, ASMTinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- Mo-molybdopterin + L-cysteine + AH2 = thio-Mo-molybdopterin + L-alanine + A + H2O
- N(6),N(6)-dimethyl-L-lysyl(4)-[histone H3] + 2 A + 2 H2O = L-lysyl(4)-[histone H3] + 2 formaldehyde + 2 AH2
Catalysed by SLC1A1, MOCOS, KDM1A, KDM1Binner side of the membrane, outer side of the membraneOne of 3 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- 3-fumarylpyruvate + H2O = fumarate + pyruvate + H(+)
Catalysed by SLC1A1, CTH, FAHD1inner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- (R)-4'-phosphopantothenate:L-cysteine ligase
- N-[(R)-4'-Phosphopantothenoyl]-L-cysteine carboxy-lyase
Catalysed by SLC1A1, PPCS, PPCDCinner side of the membrane, outer side of the membrane, cytosolOne of 2 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- transport of cysteine and glycine (cytosol to extracellular)
- glycine:oxygen oxidoreductase (deaminating)
Catalysed by SLC1A1, SLC3A2, SLC7A5, SLC7A8 and 1 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosol, peroxisome
- serotonin(out) + K(+)(in) + Na(+)(out) + H(+)(in) = serotonin(in) + K(+)(out) + Na(+)(in) + H(+)(out)
- transport of serotonin (cytosol to extracellular)
- transport of bilirubin (cytosol to extracellular)
Catalysed by SLC6A4, SLCO1A2, SLCO1B3inner side of the membrane, outer side of the membrane, extracellular space, cytosolOne of 4 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + sulfate(out) = L-aspartate(out) + sulfate(in)
- transport of oxalate and sulfate (cytosol to extracellular)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 4 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosolOne of 2 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- transport of (R)-3-hydroxybutanoate and pyruvate (cytosol to extracellular)
Catalysed by SLC1A1, CTH, SLC16A4, SLC16A5 and 4 moreinner side of the membrane, outer side of the membrane, cytosol, extracellular spaceOne of 2 routes
- serotonin(out) + K(+)(in) + Na(+)(out) + H(+)(in) = serotonin(in) + K(+)(out) + Na(+)(in) + H(+)(out)
- transport of serotonin (cytosol to extracellular)
- transport of S-glutathionyl-2-4-dinitrobenzene (cytosol to extracellular)
Catalysed by SLC6A4, SLCO1A2, SLCO1B3inner side of the membrane, outer side of the membrane, extracellular space, cytosolOne of 4 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- L-serine + pyruvate = 3-hydroxypyruvate + L-alanine
Catalysed by SLC1A1, CTH, AGXTinner side of the membrane, outer side of the membrane, cytosol
- serotonin(out) + K(+)(in) + Na(+)(out) + H(+)(in) = serotonin(in) + K(+)(out) + Na(+)(in) + H(+)(out)
- transport of GSH and serotonin (cytosol to extracellular)
- glutathione:dehydroascorbate oxidoreductase
Catalysed by SLC6A4, SLCO1A2, SLCO1B3inner side of the membrane, outer side of the membrane, extracellular space, cytosol
- serotonin(out) + K(+)(in) + Na(+)(out) + H(+)(in) = serotonin(in) + K(+)(out) + Na(+)(in) + H(+)(out)
- transport of GSH and serotonin (cytosol to extracellular)
- Formation of Homocystine
Catalysed by SLC6A4, SLCO1A2, SLCO1B3inner side of the membrane, outer side of the membrane, extracellular space, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- transport of cysteine and ornithine (cytosol to extracellular)
- L-Ornithine:2-oxo-acid aminotransferase
Catalysed by SLC1A1, SLC7A6, OATinner side of the membrane, outer side of the membrane, extracellular space, cytosol, mitochondrial matrix
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- acetyl-CoA:L-aspartate N-acetyltransferase
- Acetyl-CoA:arylamine N-acetyltransferase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 4 moreinner side of the membrane, outer side of the membrane, mitochondrial matrix, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- aceneuramate = aldehydo-N-acetyl-D-mannosamine + pyruvate
Catalysed by SLC1A1, CTH, NPLinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- acetyl-CoA:L-aspartate N-acetyltransferase
- N1,N12-diacetylspermine to N1-acetylspermine conversion
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 2 moreinner side of the membrane, outer side of the membrane, mitochondrial matrix, cytosolOne of 2 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- N(1)-methylguanosine(37) in tRNA(Phe) + pyruvate + S-adenosyl-L-methionine = 4-demethylwyosine(37) in tRNA(Phe) + 5'-deoxyadenosine + L-methionine + CO2 + H2O
Catalysed by SLC1A1, CTH, TYW1B, TYW1inner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- Mo-molybdopterin + L-cysteine + AH2 = thio-Mo-molybdopterin + L-alanine + A + H2O
- all-trans-13,14-dihydroretinol + A = all-trans-retinol + AH2
Catalysed by SLC1A1, MOCOS, RETSATinner side of the membrane, outer side of the membrane
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + sulfate(out) = L-aspartate(out) + sulfate(in)
- sulfite(in) + sulfate(out) = sulfite(out) + sulfate(in)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membraneOne of 2 routes
- Ca(2+)(out) + K(+)(out) + 4 Na(+)(in) = Ca(2+)(in) + K(+)(in) + 4 Na(+)(out)
- transport of Ca2+ and K+ (cytosol to extracellular)
- transport of D-aspartate (cytosol to extracellular)
Catalysed by SLC24A1, SLC24A5, SLC24A4, SLC24A3 and 6 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-tryptophan(out) + L-aspartate(in) = L-tryptophan(in) + L-aspartate(out)
- Transport of 3-Hydroxy-L-Kynurenine
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosolOne of 2 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- Aspartate Intake by System Asct-1 Transporter
- L-proline:(acceptor) oxidoreductase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 2 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosolOne of 2 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- transport of arginine and cysteine (cytosol to extracellular)
- L-arginine carboxy-lyase (agmatine-forming)
Catalysed by SLC1A1, SLC7A6inner side of the membrane, outer side of the membrane, extracellular space, cytosol, mitochondrial matrix
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + L-methionine(out) = L-aspartate(out) + L-methionine(in)
- N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-SH + AH2 + 2 S-adenosyl-L-methionine = 2-methylsulfanyl-N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-H + 5'-deoxyadenosine + L-methionine + A + S-adenosyl-L-homocysteine + 2 H(+)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membraneOne of 24 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- transport of cysteine and glycine (cytosol to extracellular)
- succinyl-CoA:glycine C-succinyltransferase (decarboxylating)
Catalysed by SLC1A1, SLC3A2, SLC7A5, SLC7A8 and 3 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosol, mitochondrial matrix
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-tryptophan(out) + L-aspartate(in) = L-tryptophan(in) + L-aspartate(out)
- L-tryptophan + O2 + H2O = indole-3-pyruvate + H2O2 + NH4(+)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membraneOne of 2 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + sulfate(out) = L-aspartate(out) + sulfate(in)
- Steryl-Sulfatase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 4 moreinner side of the membrane, outer side of the membrane, Golgi apparatusOne of 2 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- acetyl-CoA:L-aspartate N-acetyltransferase
- Fatty Acid Beta Oxidation (C18:3->C16:3), Mitochondrial
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 5 moreinner side of the membrane, outer side of the membrane, mitochondrial matrix
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- oxaloacetate + L-alanine = L-aspartate + pyruvate
- L-Alanine:tRNA(Ala) ligase (AMP-forming)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- transport of chloride and cysteine (cytosol to extracellular)
- transport of betaine and chloride (cytosol to extracellular)
Catalysed by SLC1A1, SLC6A14, SLC6A12inner side of the membrane, outer side of the membrane, extracellular space, cytosolOne of 3 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- transport of cysteine and histidine (cytosol to extracellular)
- L-histidine ammonia-lyase (urocanate-forming)
Catalysed by SLC1A1, SLC7A6, HALinner side of the membrane, outer side of the membrane, extracellular space, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-leucine(out) + L-aspartate(in) = L-leucine(in) + L-aspartate(out)
- L-Leucine:2-oxoglutarate aminotransferase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, mitochondrial matrixOne of 4 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- acetyl-CoA:L-aspartate N-acetyltransferase
- N1,N8-diacetylspermidine to N1-acetylspermidine conversion
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 2 moreinner side of the membrane, outer side of the membrane, mitochondrial matrix, cytosolOne of 2 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate 1-carboxy-lyase (beta-alanine-forming)
- beta-alanine:2-oxoglutarate aminotransferase
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, cytosol, mitochondrial matrix
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-aspartate(in) + L-phenylalanine(out) = L-aspartate(out) + L-phenylalanine(in)
- Phenylalanine Transaminase, Mitochondrial
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 4 moreinner side of the membrane, outer side of the membrane, mitochondrial matrixOne of 5 routes
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- L-Citrulline:L-aspartate ligase (AMP-forming)
- 2-(Nomega-L-arginino)succinate arginine-lyase (fumarate-forming)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 3 moreinner side of the membrane, outer side of the membrane, cytosolOne of 8 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-Cysteine:2-oxoglutarate aminotransferase
- 3-mercaptopyruvate sulfurtransferase (hydrogen-cyanide)
Catalysed by SLC1A1, GOT2, GOT1, MPST and 1 moreinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-cysteine hydrogen-sulfide-lyase (deaminating
- pyruvate kinase (dTDP)
Catalysed by SLC1A1, CTH, PKM, PKLRinner side of the membrane, outer side of the membrane, cytosol
- K(+)(in) + L-aspartate(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-aspartate(in) + 3 Na(+)(in) + H(+)(in)
- Aspartate Intake by System Asct-1 Transporter
- prolyl 4-hydroxylase (AKG)
Catalysed by SLC1A7, SLC1A3, SLC1A2, SLC1A1 and 4 moreinner side of the membrane, outer side of the membrane, extracellular space, cytosol, endoplasmic reticulumOne of 5 routes
- K(+)(in) + L-cysteine(out) + 3 Na(+)(out) + H(+)(out) = K(+)(out) + L-cysteine(in) + 3 Na(+)(in) + H(+)(in)
- L-glutamate:L-cysteine gamma-ligase (ADP-forming)
- gamma-glutamylcyclotransferase (gamma-glutamyl-cysteine)
Catalysed by SLC1A1, GCLC, GCLM, GGCT and 1 moreinner side of the membrane, outer side of the membrane, cytosol