LAPTM5: a novel lysosomal-associated multispanning membrane protein preferentially expressed in hematopoietic cells.
While a large body of knowledge about cell membrane proteins exists, much less is known about the repertoire and function of integral membrane proteins of intracellular organelles. In looking for novel classes of genes that are functionally important to hematopoietic cells, we have cloned the cDNA for a gene preferentially expressed in adult hematopoietic tissues. During embryonic development the gene is expressed in both hematopoietic and nonhematopoietic tissues. In cell lines the gene is expressed specifically in hematopoietic lineages, whereas in normal adult tissues the mRNA is preferentially detected at high levels in lymphoid and myeloid tissues. The predicted protein is a pentaspanner with no homology to known genes and conserved across evolution. Immunocytological and cell fractionation studies with a specific antibody revealed a protein localizing in lysosomes. The gene, provisionally named LAPTM5, maps to chromosome 1p34. The expression pattern of the gene together with preliminary evidence that the protein interacts with ubiquitin indicates that the protein may have a special functional role during embryogenesis and in adult hematopoietic cells.
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Division of Hematology/Oncology, Harvard Medical School, Boston, Massachusetts, 02215, USA.
Zhu
S
S
Ko
J L
JL
Guillemot
J C
JC
Cuervo
A M
AM
Kobayashi
H
H
Horiuchi
T
T
Lelias
J M
JM
Rowley
J D
JD
Lim
B
B
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D002874:Chromosome Mapping; D002878:Chromosomes, Human, Pair 1; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004622:Embryo, Mammalian; D005314:Embryonic and Fetal Development; D005260:Female; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D017874:Immediate-Early Proteins; D007425:Intracellular Membranes / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
D000906:Antibodies; D018076:DNA, Complementary; D017874:Immediate-Early Proteins; C484408:Laptm5 protein, mouse; D008565:Membrane Proteins; D010455:Peptides; D012333:RNA, Messenger; C100848:LAPTM5 protein, human