Cloning and expression of a new mammalian chaperonin gene from a multipotent hematopoietic progenitor clone.
Molecular chaperones assist in the folding and assembly of proteins in cells. Although chaperonins have been shown in prokaryotes, mitochondria, and chloroplasts long-ago, a cytoplasmic heteromeric chaperonin complex was isolated only recently and found to contain at least five to six polypeptides, one of which was identified as the product of the T complex polypeptide-1 (TCP-1) gene. We have isolated and cloned a novel gene called A45 from a cDNA library constructed from poly (A)+ RNA of a multipotent hematopoietic progenitor clone. The A45 cDNA encodes a predicted polypeptide of M(r) 58,118 that exhibits 32% overall amino acid sequence identity to TCP-1 and contains the putative adenosine triphosphate-binding domain and two characteristic consensus regions that are conserved in all chaperonins. The A45 gene is expressed in hematopoietic precursors cells at a much higher level than in nonhematopoietic cells and tissues. We conclude that A45 represents a new member of the mammalian chaperonins that is involved in the folding and assembly of polypeptides.
Xie
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Department of Immunology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Palacios
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001854:Bone Marrow Cells; D018833:Chaperonins / Q000235:genetics*; D003001:Cloning, Molecular; D015870:Gene Expression; D006412:Hematopoietic Stem Cells; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D012333:RNA, Messenger; D018833:Chaperonins