K. Morishige et al., Secretagogue-induced exocytosis recruits G protein-gated K+ channels to plasma membrane in endocrine cells, J BIOL CHEM, 274(12), 1999, pp. 7969-7974
Stimulation-regulated fusion of vesicles to the plasma membrane is an essen
tial step for hormone secretion but may also serve for the recruitment of f
unctional proteins to the plasma membrane. While studying the distribution
of G protein-gated K+ (K-G) channels in the anterior pituitary lobe, we fou
nd K-G channel subunits Kir3.1 and Kir3.4 localized on the membranes of int
racellular dense core vesicles that contained thyrotropin. Stimulation of t
hese thyrotroph cells with thyrotropin-releasing hormone provoked fusion of
vesicles to the plasma membrane, increased expression of Kir3.1 and Kir3.4
subunits in the plasma membrane, and markedly enhanced K-G currents stimul
ated by dopamine and somatostatin, These data indicate a novel mechanism fo
r the rapid insertion of functional ion channels into the plasma membrane,
which could form a new type of negative feedback control loop for hormone s
ecretion in the endocrine system.