HUMAN ERYTHROCYTE BAND 7.2B IS PREFERENTIALLY LABELED BY A PHOTOREACTIVE PHOSPHOLIPID

A head-group modified, photoreactive analog of phosphatidylethanolamin e, 1,2-dilauryl-sn-glycero-3-phosphatidylethanolamine ([I-125]-N-ASA-D LPE). has been used in photoaffinity labeling studies of proteins of t he human erythrocyte membrane. [I-125]-N-ASA-DLPE was shown to be pref erentially incorporated into a protein with an apparent molecular weig ht of 31 kDa. protein sequencing and immunoprecipitation were used to identify this protein as the erythrocyte membrane protein, and 7.2b or stomatin. A sulphydryl-reactive ligand, -N-[2-(2-pyridinyldithio)ethy l]-benzenepropanamide ([I-125]-PDA), was also shown to preferentially label band 7.2b, We propose that band 7.2b may act as a site of transb ilayer reorientation of membrane phospholipids. (C) 1996 Academic Pres s, Inc.