Expression cloning of a cDNA encoding a novel murine B cell activation marker. Homology to human CD38.
A rat mAb (NIM-R5) has recently been prepared against a novel murine B cell activation marker. We report here isolation of a cDNA (1-19) encoding the B cell-derived protein recognized by NIM-R5 antibody. This cDNA contains an open reading frame that encodes a polypeptide of 304 amino acids with a predicted molecular weight of 34,500. The existence of a 22-amino acid hydrophobic region located 23 amino acids from the amino terminal of the deduced protein, together with four potential N-linked glycosylation sites, characterize the deduced protein encoded by I-19 cDNA as a typical type II transmembrane glycoprotein. Although I-19 cDNA appears to encode a novel murine protein, its nucleotide sequence and deduced amino acid sequence show approximately 70% homology to the previously reported sequence of human CD38, suggesting that I-19 cDNA encodes either the mouse homologue of CD38 or a closely related protein. Northern blot analysis of the expression of this cDNA product in a variety of cell types, together with immunoprecipitation of the recombinant protein expressed in BaF3 cells, indicated that I-19 cDNA encodes not only the epitope recognized by NIM-R5 but also a protein that is indistinguishable biochemically and in terms of distribution from the murine B cell activation marker recognized by NIM-R5 antibody. Chromosomal mapping studies have localized this locus to the proximal region of mouse chromosome 5. We anticipate that the availability of probes for the murine B cell activation marker recognized by NIM-R5, and the recombinant protein itself, will greatly aid efforts to define the role of this molecule in murine B cell development.
DNAX Research Institute, Palo Alto, CA 94304.
N
N
Harada
L
L
Santos-Argumedo
R
R
Chang
J C
JC
Grimaldi
F E
FE
Lund
C I
CI
Brannan
N G
NG
Copeland
N A
NA
Jenkins
A W
AW
Heath
R M
RM
Parkhouse
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000235:genetics*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics*; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data
D015703:Antigens, CD; D000943:Antigens, Differentiation; D000944:Antigens, Differentiation, B-Lymphocyte; D008562:Membrane Glycoproteins; D004247:DNA; D036541:ADP-ribosyl Cyclase; C498155:Cd38 protein, mouse; D051997:ADP-ribosyl Cyclase 1