A synthetic peptide substrate specific for casein kinase‐1

Open Access
Publisher Website
Google Scholar
Abstract
The synthetic peptide, Asp‐Asp‐Asp‐Glu‐Glu‐Ser‐Ile‐Thr‐Arg‐Arg, derived from the phosphorylation site of casein kinase‐1 (CK‐1) in β‐casein A2, is readily phosphorylated by CK‐1, but not by casein kinase‐2 (CK‐2), cyclic AMP‐dependent protein kinase, protein kinsae C, phosphorylase kinase and protein kinase Fa. Phosphorylation by CK‐1 occurs only at Ser‐6, Thr‐8 being unaffected. The K m for the peptide is higher (1 mM) than for β‐casein A2 (40 μM), while the V maxis quite comparable. This is the first synthetic peptide substrate for CK‐1 described so far, and can be used for the rapid and specific estimation of CK‐1 activity in crude extracts.