F. Kalkbrenner et al., SUBUNIT COMPOSITION OF G(O) PROTEINS FUNCTIONALLY COUPLING GALANIN RECEPTORS TO VOLTAGE-GATED CALCIUM CHANNELS, EMBO journal, 14(19), 1995, pp. 4728-4737
The neuropeptide galanin is widely expressed in the central nervous sy
stem and other tissues and induces different cellular reactions, e.g.
hormone release from pituitary and inhibition of insulin release from
pancreatic B cells. By microinjection of antisense oligonucleotides we
studied the question as to which G proteins mediate the galanin-induc
ed inhibition of voltage-gated Ca2+ channels in the rat pancreatic B-c
ell line RINm5F and in the rat pituitary cell line GH(3). Injection of
antisense oligonucleotides directed against alpha(o1), beta(2), beta(
3), gamma(2), and gamma(4) G protein subunits reduced the inhibition o
f Ca2+ channel current which was induced by galanin, whereas no change
was seen after injection of cells with antisense oligonucleotides dir
ected against alpha(i), alpha(q), alpha(11), alpha(14), alpha(15), bet
a(1), beta(4), gamma(1), gamma(3), gamma(5), or gamma(7) G protein sub
units or with sense control oligonucleotides. In view of these data an
d of previous results, we conclude that the galanin receptors in GH(3)
and in RINm5F cells couple mainly to the G(o) protein consisting of a
lpha(o1)beta(2) gamma(2), to inhibit Ca2+ channels and use alpha(o1)be
ta(3) gamma(4) less efficiently. The latter G protein composition was
previously shown to be used by muscarinic M(4) receptors to inhibit Ca
2+ channels.