Characterization of MDGA1, a novel human glycosylphosphatidylinositol-anchored protein localized in lipid rafts

Abstract

We report the characterization of the novel human protein MDGA1 encoded by MDGA1 (MAM domain containing glycosylphosphatidyl-inositol anchor-1) gene, firstly ten tied as GPIM.MDGA1 has been mapped to 6p21 and it is expressed inhuman tissues andturnors. The deduced polypeptide consists of 955 amino acids and exhibits structural features found in different types of cell adhesion molecules (CAMs), such as the presence of both immunoglobulin domains and a MAM domain or the capacity to anchor to the cell membrane by a GPI (glycosylphosphatidylinositol) motif. Our results demonstrate that human MDGA1 (hMDGA1) is localized in the membrane of eukaryotic cells. The protein follows the secretion pathway and finally it is retained in the cell membrane by a GPI anchor, susceptible to be cleavaged by phospholipase C (PI-PLC). Moreover, our results reveal that hMDGA1 is localized specifically into membrane microdomains known as lipid rafts. Finally, as other proteins of the secretory pathway, hMDGA1 undergoes other post-translational modification consisting of N-glycosylation. (c) 2005 Elsevier Inc. All rights reserved.