STRUCTURE, ORGANIZATION, AND CHROMOSOMAL MAPPING OF THE GENE ENCODINGMACROSIALIN, A MACROPHAGE-RESTRICTED PROTEIN

Murine macrosialin and its human homologue CD68 are heavily glycosylat ed transmembrane proteins expressed specifically in macrophages and ma crophage-related cells. Macrosialin is predominantly a late endosomal protein but is also found on the cell surface where it binds oxidized LDL, an important factor in atherogenesis. We have cloned and sequence d the murine macrosialin gene (Cd68) and localized it by linkage analy sis to chromosome 11, The gene is 1908 nucleotides long from the start site of transcription to the end of the 3'UTR. It has six exons, whic h range in size from 79 to 434 nucleotides. The promoter lacks a class ical TATA box but contains other protein binding sites consistent with preferential monocyte/macrophage gene expression. Although the functi on of macrosialin is unknown, it might play a role in lipoprotein regu lation given its binding of oxidized LDL in vitro and its colocalizati on to a region on chromosome 11 involved in the control of HDL levels. (C) 1998 Academic Press.