GTP must bind to the "α" subunit in order for a G protein to be activated as a consequence of hormone binding.
Discussion:
Over 40 years ago, regulatory GTPases triggered by rhodopsin and beta-adrenergic receptors were initially identified as heterotrimeric G - proteins alpha subunits (G).
The family's three prototypical members—Gs, Gi, and transducin (Gt), were purified and enzymatically described within ten years. Heterotrimeric G - proteins alpha subunits (G) are a distinctive type of Ras superfamily guanine nucleotide binding proteins22.
The tertiary and quaternary shape, activation and signaling processes, and kinetic characteristics of G make them special. G subunits, like all other representatives of the Ras superfamily, consist of a six-stranded homologous core with helices connecting the majority of the strands in succession.
Therefore the correct choice is an option (A), i.e., GTP and α.
The complete question is:
Activation of a G protein in response to hormone binding requires binding of _____ to the _____ subunit.
Glucose is then burned in her body for energy. One of the body parts that needs this energy is the heart, which beats due to electrical impulses. A byproduct of this glucose breakdown is the heat that warms her body and is later released.
