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Titolo:
Identification of G protein-coupled, inward rectifier potassium channel gene products from the rat anterior pituitary gland
Autore:
Gregerson, KA; Flagg, TP; ONeill, TJ; Anderson, M; Lauring, O; Horel, JS; Welling, PA;
Indirizzi:
Univ Maryland, Dept Obstet, Baltimore, MD 21201 USA Univ Maryland Baltimore MD USA 21201 Dept Obstet, Baltimore, MD 21201 USA Univ Maryland, Dept Gynecol, Baltimore, MD 21201 USA Univ Maryland Baltimore MD USA 21201 ept Gynecol, Baltimore, MD 21201 USA Univ Maryland, Dept Reprod Sci, Baltimore, MD 21201 USA Univ Maryland Baltimore MD USA 21201 Reprod Sci, Baltimore, MD 21201 USA Univ Maryland, Ctr Studies Reprod, Baltimore, MD 21201 USA Univ Maryland Baltimore MD USA 21201 dies Reprod, Baltimore, MD 21201 USA
Titolo Testata:
ENDOCRINOLOGY
fascicolo: 7, volume: 142, anno: 2001,
pagine: 2820 - 2832
SICI:
0013-7227(200107)142:7<2820:IOGPIR>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
RECTIFYING K+-CHANNEL; DOPAMINE RECEPTOR ACTIVATION; BETA-GAMMA-SUBUNITS; PERTUSSIS TOXIN; D2-DOPAMINE RECEPTOR; PROLACTIN SECRETION; FUNCTIONAL EXPRESSION; WHOLE-CELL; I-KACH; BINDING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
54
Recensione:
Indirizzi per estratti:
Indirizzo: Gregerson, KA Univ Maryland, Dept Obstet Gynecol & Reprod Sci, 11-007 Bressler Res Bldg,65 W Baltimore St, Baltimore, MD 21201 USA Univ Maryland 11-007 Bressler Res Bldg,65 W Baltimore St Baltimore MD USA 21201
Citazione:
K.A. Gregerson et al., "Identification of G protein-coupled, inward rectifier potassium channel gene products from the rat anterior pituitary gland", ENDOCRINOL, 142(7), 2001, pp. 2820-2832

Abstract

Dopamine (DA) is a physiological regulator of PRL secretion, exerting tonic inhibitory control. DA activates an inward rectifier KI (IRK) channel in rat lactotropes, causing membrane hyperpolarization and inhibition of Ca2+-dependent action potentials. Both the activation of this effector Kf channel and the inhibition of PRL release are mediated by D-2-type receptor activation and pertussis toxin-sensitive G proteins. To study the molecular basis of this physiologically relevant channel, a homology-based PCR approach was employed to identify members of the IRK channel family expressed in the anterior pituitary gland. Nondegenerate primers corresponding to regions specific for IRK channels known to be G protein activated (GIRKs; gene subfamily Kir 3.0) were synthesized and used in the PCR with reverse transcribed female rat anterior pituitary messenger RNA as the template. PCR products of predicted sizes for Kir 3.1, 3.2, and 3.4 were consistently observed by ethidium bromide staining after 16 amplification cycles. The identities of the products were confirmed by subcloning and sequencing. Expression of eachof these gene products in anterior pituitary was confirmed by Northern blot analysis. Functional analysis of the GIRK proteins was performed in the heterologous expression system, Xenopus laevis oocytes. Macroscopic K+ currents were examined in oocytes injected with different combinations of Kir 3.0 complementary RNA (cRNA) and G protein subunit (beta (1)gamma (2)) cRNA. The current-voltage relationships demonstrated strong inward rectification for each individual and pairwise combination of GIRK channel subunits. Oocytes coinjected with any pair of GIRK subunit cRNA exhibited significantly larger inward K+ currents than oocytes injected with only one GIRK channel subtype. Ligand-dependent activation of only one of the GIRK combinations (GIRK1 and GIRK4) was observed when channel subunits were coexpressed with the D, receptor in Xenopus oocytes. Dose-response data fit to a Michaelis-Menten equation gave an apparent fb similar to that for DA binding in anteriorpituitary tissue. GIRK1 and GIRX4 proteins were coimmunoprecipitated from anterior pituitary lysates, confirming the presence of native GIRK1/GIRK4 oligomers in this tissue. These data indicate that GIRK1 and GIRK4 are excellent candidate subunits for the D-2-activated, G protein-gated channel in pituitary lactotropes, where they play a critical role in excitation-secretion coupling.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/01/20 alle ore 08:57:34