Cloning and characterization of 5'-end alternatively spliced human cholecystokinin-B receptor mRNAs.
We report here the cloning and characterization of a 5'-end alternatively spliced human cholecystokinin-B (CCK-B) receptor mRNA. The 5'-end of this CCK-B receptor transcript (termed CCK-BRtx) consisted of exon Ia, present in the ordinary full-length CCK-B receptor mRNA (CCK-BRwt), and exon Ib, present in a previously described 5'-end alternatively spliced CCK-B receptor mRNA (CCK-BRt). A short open reading frame preceded the AUG translation initiation codon of the CCK-BRtx. Transfection of COS-7 cells with the CCK-BRtx or CCK-BRt cDNAs did not lead to the appearance of peptidergic and non-peptidergic binding sites. Cell free in vitro translation yielded proteins of approximately 44 kDa (CCK-B receptor) and 40 kDa (CCK-BRt receptor) whereas no 40 kDa product was detected from the cloned CCK-BRtx cDNA. Instead, a protein product of approximately 9 kDa was visualized, the size corresponding to the predicted protein encoded by the short open reading frame. The alternatively spliced CCK-B receptor transcripts were concomitantly expressed with the ordinary full-length CCK-B receptor mRNA in the brain, pancreas, and stomach. The possibility that such transcripts are translated in vivo into truncated CCK-B receptors is discussed.
Monstein
H J
HJ
Division of Clinical Microbiology, Molecular Biology Laboratory, LMO, University Hospital, Linköping, Sweden.
Nilsson
I
I
Ellnebo-Svedlund
K
K
Svensson
S P
SP
D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001570:Benzodiazepinones / Q000378:metabolism; D001667:Binding, Competitive; D019556:COS Cells; D002766:Cholecystokinin / Q000378:metabolism; D003001:Cloning, Molecular; D005755:Gastrins / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010671:Phenylurea Compounds / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D011949:Receptors, Cholecystokinin / Q000737:chemistry / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014162:Transfection
D001570:Benzodiazepinones; D005755:Gastrins; D010671:Phenylurea Compounds; D012333:RNA, Messenger; D011949:Receptors, Cholecystokinin; C090649:L 740093; C058121:L 365260; C013550:gastrin 17; D002766:Cholecystokinin