Inhibitory effect of transfer RNA on protein kinases from baker's yeast and rat skeletal muscle

Sephadex G-200 gel filtration of DNA cellulose-treated crude extracts of rat skeletal muscle, revealed a broad peak-fraction of tRNA-inhibitory protein kinases (PK) coeluted endogenous substrates. In comparison, the elution profile of baker's yeast exhibited multiple peak-fractions of tRNA-inhibiting PK. Various tRNA all showed inhibition to PK. In the presence of regulatory subunit of cyclic AMP-dependent protein kinase, tRNA did not exert synergetic inhibition on PK. Moreover, the interaction of tRNA with active muscle PK fractions could not be monitored by the increment of absorbance at 340 nm. tRNA had no significant regulatory effect on the phosphorylation of actin and myosin.