Analysis Note

One unit will transfer 1 nanomole of phosphate from ³²P-ATP to kemptide substrate per minute at pH 7.4 at 30 °C (measured by a radioactive filter-binding assay). K_m (ATP) = 25 µM at 30 °C, pH 7.4. K_m (kemptide) = 42 µM (33 µg/ml) at 30 °C, pH 7.4.

Biochem/physiol Actions

Ubiquitous serine-threonine kinase that phosphorylates a broad spectrum of substrates, and regulates many cellular processes. The catalytic subunit is released following binding of cyclic AMP to the regulatory subunits of the PKA holoenzyme. The free catalytic subunit has intrinsic activity and does not require added cyclic AMP.

Physical form

Solution in 30 mM potassium phosphate buffer, pH 7.4, containing 50% glycerol, 150 mM KCl, 1 mM EDTA, and 1 mM DTT.