title: Identification and characterization of five-transmembrane isoforms of human vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide receptors.
abstract: The seven-transmembrane (7TM) G-protein-coupled neuroendocrine receptors VPAC1 (HGNC approved gene symbol VIPR1) and VPAC2 (HGNC approved gene symbol VIPR2) are expressed in different tissues and involved in the regulation of important biological functions. We now report the identification and characterization of novel five-transmembrane(5TM) forms of both human VPAC1 and human VPAC2. These alternatively spliced variant mRNAs result from the skipping of exons 10/11, spanning the third intracellular loop, the fourth extracellular loop, and the transmembrane regions 6 and 7, producing in-frame 5TM receptors predicted to lack a G-protein-binding motif. RT-PCR showed that these 5TM receptors are differentially expressed in transformed and normal cells. Translation of the 5TM protein was demonstrated by transfection and expression in CHO cells. Following agonist stimulation, differential signaling of the 7TM versus 5TM forms was shown both for the activation of adenylate cyclase and for tyrosine phosphorylation. The identification of these splice variants in various cells and their expression and differential signal transduction compared to the 7TM form suggest that these novel receptors have biological relevance.
authors.affiliation: Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8; Research and Development, Canadian Blood Services, Toronto, ON, Canada M5G 2M1.
authors.forename: Payman Baradar
authors.initials: PB
authors.lastname: Bokaei
authors.affiliation: Research and Development, Canadian Blood Services, Toronto, ON, Canada M5G 2M1; Department of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8.
authors.forename: Xue-Zhong
authors.initials: XZ
authors.lastname: Ma
authors.affiliation: Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8; Research and Development, Canadian Blood Services, Toronto, ON, Canada M5G 2M1.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Byczynski
authors.affiliation: Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8; Research and Development, Canadian Blood Services, Toronto, ON, Canada M5G 2M1.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Keller
authors.affiliation: Research and Development, Canadian Blood Services, Toronto, ON, Canada M5G 2M1.
authors.forename: Darinka
authors.initials: D
authors.lastname: Sakac
authors.affiliation: Research and Development, Canadian Blood Services, Toronto, ON, Canada M5G 2M1.
authors.forename: Soad
authors.initials: S
authors.lastname: Fahim
authors.affiliation: Institute of Medical Science, University of Toronto, Toronto, ON, Canada M5S 1A8; Research and Development, Canadian Blood Services, Toronto, ON, Canada M5G 2M1; Department of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada M5S 1A8; Division of Cell and Molecular Biology, Toronto General Research Institute, 67 College Street, Toronto, ON, Canada M5G 2M1. Electronic address: don.branch@utoronto.ca.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Branch
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D005786:Gene Expression Regulation; D014644:Genetic Variation; D006801:Humans; D007963:Leukocytes, Mononuclear; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051239:Receptors, Vasoactive Intestinal Peptide, Type II / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D020033:Protein Isoforms; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I