The term "alpha subunit" refers to a part or component of a larger unit or molecule that holds a higher position or importance. It can be considered as a main or dominant part of a group or structure. Full definition
Palmitoylation at Cys - 416 is important for recruitment at both plasma membrane and lipid rafts and association with G protein alpha subunits. (swisspalm.org)
Heterotrimeric guanine nucleotide - binding regulatory proteins (G proteins) dissociate into guanosine triphosphate (GTP)- bound alpha subunits and a complex of beta and gamma subunits after interaction with receptors. (science.sciencemag.org)
The GTP - alpha subunit complex activates appropriate effectors, such as adenylyl cyclase, retinal phosphodiesterase, phospholipase C, and ion channels. (science.sciencemag.org)