| http://purl.uniprot.org/citations/15955806 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | http://purl.uniprot.org/core/Journal_Citation |
| http://purl.uniprot.org/citations/15955806 | http://www.w3.org/2000/01/rdf-schema#comment | "The mechanisms involved in glucose regulation of insulin secretion by ATP-sensitive (K(ATP)) and calcium-activated (K(CA)) potassium channels have been extensively studied, but less is known about the role of voltage-gated (K(V)) potassium channels in pancreatic beta-cells. The incretin hormone, glucose-dependent insulinotropic polypeptide (GIP) stimulates insulin secretion by potentiating events underlying membrane depolarization and exerting direct effects on exocytosis. In the present study, we identified a novel role for GIP in regulating K(V)1.4 channel endocytosis. In GIP receptor-expressing HEK293 cells, GIP reduced A-type peak ionic current amplitude of K(V)1.4 via activation of protein kinase A (PKA). Using mutant forms of K(V)1.4 with Ala-Ser/Thr substitutions in a potential PKA phosphorylation site, C-terminal phosphorylation was shown to be linked to GIP-mediated current amplitude decreases. Proteinase K digestion and immunocytochemical studies on mutant K(V)1.4 localization following GIP stimulation demonstrated phosphorylation-dependent rapid endocytosis of K(V)1.4. Expression of K(V)1.4 protein was also demonstrated in human beta-cells; GIP treatment resulting in similar decreases in A-type potassium current peak amplitude to those in HEK293 cells. Transient overexpression in INS-1 beta-cells (clone 832/13) of wild-type (WT) K(V)1.4, or a T601A mutant form resistant to PKA phosphorylation, resulted in reduced glucose-stimulated insulin secretion; WT K(V)1.4 overexpression potentiated GIP-induced insulin secretion, whereas this response was absent in T601A cells. These results strongly support an important novel role for GIP in regulating K(V)1.4 cell surface expression and modulation of A-type potassium currents, which is likely to be critically important for its insulinotropic action."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.org/dc/terms/identifier | "doi:10.1074/jbc.m504913200"xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/author | "Kim S.J."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/author | "Han J.S."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/author | "Choi W.S."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/author | "Fedida D."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/author | "Warnock G."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/author | "McIntosh C.H."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/date | "2005"xsd:gYear |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/name | "J Biol Chem"xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/pages | "28692-28700"xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/title | "A novel mechanism for the suppression of a voltage-gated potassium channel by glucose-dependent insulinotropic polypeptide: protein kinase A-dependent endocytosis."xsd:string |
| http://purl.uniprot.org/citations/15955806 | http://purl.uniprot.org/core/volume | "280"xsd:string |
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