Transbilayer movement of phosphatidylserine in erythrocytes: inhibition of transport and preferential labeling of a 31 000-dalton protein by sulfhydryl reactive reagents

Abstract

A series of labeled thiolation reagents were synthesized on the basis of the parent structure pyridylthioethylamine (PDA). These compounds specifically and reversibly inhibit the active intrabilayer transport of phosphatidylserine (PS) in human red blood cells. The binding of PDA to cells can be quantified since the thiol-disulfide exchange reaction yields a chromophore. In addition, the presence of a primary amine makes it amenable to derivatization with a variety of compounds. An iodinated derivative of PDA preferentially labeled a 31,000-dalton red blood cell peptide. The labeled component, which may repesent the PS transporter, comigrated with integral membrane protein band 7.