a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol 4-phosphate)(out) + a 1,2-diacyl-sn-glycero-3-phospho-L-serine(in) = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol 4-phosphate)(in) + a 1,2-diacyl-sn-glycero-3-phospho-L-serine(out) — reaction