title: Molecular cloning and expression of the Modulatory subunit of the cyclic nucleotide-gated cation channel.
abstract: The cDNA of three variants of a cyclic nucleotide-gated (CNG) channel modulatory subunit (CNG4c-CNG4e) has been cloned. CNG4c, CNG4d, and CNG4e differ slightly from each other within an amino-terminal sequence that was originally reported as part of the bovine retinal glutamic acid-rich protein (GARP). The core region of CNG4 is homologous to the second subunit of the human rod photoreceptor channel (hRCNC2b), suggesting that both proteins are alternatively spliced products of the bovine and human homologue of the same gene. CNG4 transcripts are present in retina, testis, kidney, heart, and brain. Expression of CNG4 in HEK293 cells did not lead to detectable currents. Coexpression of CNG4 with the principal subunit of the bovine testis CNG channel (CNG3) resulted in currents which differed in several aspects from that induced by CNG3 alone. The heterooligomeric CNG3/CNG4 and the homooligomeric CNG3 channels were modified by Ca2+-calmodulin and some calmodulin antagonists. The results suggest that CNG4 forms functional heterooligomeric channels with CNG3 in vitro and probably also in intact tissues.
authors.affiliation: Institut für Pharmakologie and Toxikologie der Technischen Universität Munchen, Federal Republic of Germany.
authors.forename: M
authors.initials: M
authors.lastname: Biel
authors.forename: X
authors.initials: X
authors.lastname: Zong
authors.forename: A
authors.initials: A
authors.lastname: Ludwig
authors.forename: A
authors.initials: A
authors.lastname: Sautter
authors.forename: F
authors.initials: F
authors.lastname: Hofmann
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002412:Cations; D002417:Cattle; D002460:Cell Line; D003001:Cloning, Molecular; D054815:Cyclic Nucleotide-Gated Cation Channels; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009712:Nucleotides, Cyclic / Q000378:metabolism; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D002147:Calmodulin; D002412:Cations; D054815:Cyclic Nucleotide-Gated Cation Channels; D017931:DNA Primers; D018076:DNA, Complementary; D007473:Ion Channels; D009712:Nucleotides, Cyclic; D012333:RNA, Messenger; D002118:Calcium