Myelin Basic Protein (MHP4-14) TFA, a synthetic peptide comprising residues 4-14 of myelin basic protein, is a very selective PKC substrate (Km=7 μM). Myelin Basic Protein TFA is not phosphorylated by cyclic AMP-dependent protein kinase, casein kinases I and II, Ca2+/calmodulin-dependent protein kinase II, or phosphorylase kinase, and can be routinely used for the assay of protein kinase C with low background in the crude tissue extracts[1][2].
Once MBP4-14 is phosphorylated, it is not dephosphorylated by okadaic acid-sensitive phosphatases (protein phosphatases 1, 2A and 3) or other protein phosphatases such as calcineurin and/or PP 2C present in hippocampal homogenates. Therefore, MBP4-14 can be used for PKC assay in crude extracts of neural tissue[1].
[1]. Farrar YJ, et al. A phosphatase resistant substrate for the assay of protein kinase C in crude tissue extracts. Biochem Biophys Res Commun. 1991;180(2):694-701. [2]. Yasuda I, et al. A synthetic peptide substrate for selective assay of protein kinase C. Biochem Biophys Res Commun. 1990;166(3):1220-1227.