N- and P/Q-type Ca2+ channels in adrenal chromaffin cells.
Ca2+ is the most ubiquitous second messenger found in all cells. Alterations in [Ca2+]i contribute to a wide variety of cellular responses including neurotransmitter release, muscle contraction, synaptogenesis and gene expression. Voltage-dependent Ca2+ channels, found in all excitable cells (Hille 1992), mediate the entry of Ca2+ into cells following depolarization. Ca2+ channels are composed of a large pore-forming subunit, called the alpha1 subunit, and several accessory subunits. Ten different alpha1 subunit genes have been identified and classified into three families, Ca(v1-3) (Dunlap et al. 1995, Catterall 2000). Each alpha1 gene produces a unique Ca2+ channel. Although chromaffin cells express several different types of Ca2+ channels, this review will focus on the Cav(2.1) and Cav(2.2) channels, also known as P/Q- and N-type respectively (Nowycky et al. 1985, Llinas et al. 1989b, Wheeler et al. 1994). These channels exhibit physiological and pharmacological properties similar to their neuronal counterparts. N-, P/Q and to a lesser extent R-type Ca2+ channels are known to regulate neurotransmitter release (Hirning et al. 1988, Horne & Kemp 1991, Uchitel et al. 1992, Luebke et al. 1993, Takahashi & Momiyama 1993, Turner et al. 1993, Regehr & Mintz 1994, Wheeler et al. 1994, Wu & Saggau 1994, Waterman 1996, Wright & Angus 1996, Reid et al. 1997). N- and P/Q-type Ca2+ channels are abundant in nerve terminals where they colocalize with synaptic vesicles. Similarly, these channels play a role in neurotransmitter release in chromaffin cells (Garcia et al. 2006). N- and P/Q-type channels are subject to many forms of regulation (Ikeda & Dunlap 1999). This review pays particular attention to the regulation of N- and P/Q-type channels by heterotrimeric G-proteins, interaction with SNARE proteins, and channel inactivation in the context of stimulus-secretion coupling in adrenal chromaffin cells.
Fox
A P
AP
Department of Neurobiology, Pharmacology and Physiology, University of Chicago, Chicago, IL 60637, USA. aaronfox@uchicago.edu
Cahill
A L
AL
Currie
K P M
KP
Grabner
C
C
Harkins
A B
AB
Herring
B
B
Hurley
J H
JH
Xie
Z
Z
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020864:Calcium Channels, N-Type / Q000378:metabolism*; D020865:Calcium Channels, P-Type / Q000378:metabolism*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D019439:Chromaffin Cells / Q000378:metabolism*; D005089:Exocytosis; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D018408:Patch-Clamp Techniques; D050600:SNARE Proteins / Q000378:metabolism
D020864:Calcium Channels, N-Type; D020865:Calcium Channels, P-Type; D050600:SNARE Proteins; D019204:GTP-Binding Proteins; D002118:Calcium