A truncated isoform of human CCK-B/gastrin receptor generated by alternative usage of a novel exon.
An isoform cDNA of CCK-B/gastrin receptor was isolated from human stomach. This cDNA differed from initially cloned cDNA only in the 5'-end region and encoded a truncated isoform (delta CCK-B) in which the putative N-terminal extracellular domain of the CCK-B/gastrin receptor was completely lost. Isolation of genomic CCK-B/gastrin receptor DNA revealed that this transcript is generated by alternative usage of a novel exon, termed exon 1b. Human stomach expressed both transcripts of delta CCK-B and entire CCK-B/gastrin receptor (CCK-BR), whereas human stomach cancer cell line AGS exclusively expressed delta CCK-B transcripts. Transfection of COS-7 with delta CCK-B cDNA led to the appearance of binding sites for 125I-CCK-8. Its ligand selectivity was different from that of CCK-BR. These results suggest the molecular diversity in CCK-B/gastrin receptor subtypes.
Miyake
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Molecular Medicine Research Laboratories, Yamanouchi Pharmaceutical Co. Ltd, Tukuba-city, Japan.
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D015139:Blotting, Southern; D002460:Cell Line; D002522:Chlorocebus aethiops; D004247:DNA / Q000302:isolation & purification / Q000378:metabolism; D017931:DNA Primers; D018076:DNA, Complementary; D005091:Exons; D005753:Gastric Mucosa / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D011949:Receptors, Cholecystokinin / Q000096:biosynthesis* / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D012844:Sincalide / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D011949:Receptors, Cholecystokinin; D011994:Recombinant Proteins; D004247:DNA; D012844:Sincalide