although [ atp ] declined significantly during hypoxia ( from 35 to 25 nmol/mg ) , the decline in [ gtp ] was marginal ( 4.3 to 3.9 nmol/mg ) , making it unlikely that substrate for guanine nucleotide regulatory protein was limiting for beta-adrenergic signal transduction .
C0086376
guanine nucleotide regulatory protein
C0037083
signal transduction