High-affinity folate binding in human liver membranes

Abstract

High-affinity binding of 3H-folate in Triton X-100 solubilized membranes of human liver displayed characteristics, e.g. apparent positive cooperativity, which are typical of specific folate binding. Ultrogel AcA 44 chromatography of solubilized membranes saturated with 3H-folate revealed a major peak of 100 kDa and a minor peak of 25 kDa. The 100 kDa peak could represent a hydrophobic membrane associated molecular form of the protein. This notion was supported by the fact that the two peaks had identical molecular weights as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis with immunoblotting.