LAPTM5 - A NOVEL LYSOSOMAL-ASSOCIATED MULTISPANNING MEMBRANE-PROTEIN PREFERENTIALLY EXPRESSED IN HEMATOPOIETIC-CELLS

While a large body of knowledge about cell membrane proteins exists, m uch less is known about the repertoire and function of integral membra ne proteins of intracellular organelles. In looking for novel classes of genes that are functionally important to hematopoietic cells, we ha ve cloned the cDNA for a gene preferentially expressed in adult hemato poietic tissues, During embryonic development the gene is expressed in both hematopoietic and nonhematopoietic tissues. In cell lines the ge ne is expressed specifically in hematopoietic lineages, whereas in nor mal adult tissues the mRNA is preferentially detected at high levels i n lymphoid and myeloid tissues. The predicted protein is a pentaspanne r with no homology to known genes and conserved across evolution, Immu nocytological and cell fractionation studies with a specific antibody revealed a protein localizing in lysosomes. The gene, provisionally na med LAPTM5, maps to chromosome 1p34. The expression pattern of the gen e together with preliminary evidence that the protein interacts with u biquitin indicates that the protein may have a special functional role during embryogenesis and in adult hematopoietic cells. (C) 1996 Acade mic Press, Inc.