Alpha-2 adrenoceptor:Catecholamine Alpha-2 adrenoceptor Alpha-2 adrenoceptors bind catecholamines Alpha-2 adrenoceptors couple with G protein alpha-i subtype which decreases adenylyl cyclase activity, thus reducing cAMP intracellular levels resulting in smooth muscle contraction. There are three alpha-2 subtypes in humans; 2A (Kobilka BK et al, 1987), 2B (Weinshank RL et al, 1990) and 2C (Hirasawa A et al, 1993). Authored: Jassal, B, 2009-02-10 10:07:58 Edited: Jassal, B, 2009-02-10 10:07:58 Pubmed2172775 Pubmed2823383 Pubmed8396931 Reactome Database ID Release 43390663 Reactome, http://www.reactome.org ReactomeREACT_17002 Reviewed: D'Eustachio, P, 2009-03-02 09:24:35 Catecholamine