phosphorylase kinase

Phosphorylase Kinase β-Subunit Fragment (420-436) is a peptide fragment (430-436) derived from the β-Subunit of phosphorylase kinase. Phosphorylase kinase, a serine/threonine-specific protein kinase, plays a crucial role in the activation of glycogen phosphorylase for the release of glucose-1-phosphate from glycogen[1].

The cyanobacterium Nodularia spumigena often contaminates the drinking water of rural communities in developing countries and accumulates in mussels, flounder, and cod from the northern Baltic Sea. Nodularin is a hepatotoxic monocylic pentapeptide produced by the N. spumigena. It is a potent inhibitor of protein phosphatase types 1 (PP1) and 2A (PP2A), exhibiting IC50 values of 1.8 and 0.026 nM, respectively. PP2B is inhibited to a lesser extent with an IC50 of 1.8 μM. No apparent inhibitory effect is observed with PP2C, alkaline phosphatase, acid phosphatase, insulin receptor tyrosine kinase, protein kinase A, phosphorylase kinase, or protein kinase C.

Malantide TFA 是一种合成的十二肽，由被磷酸化酶激酶β亚基上的PKA 磷酸化的位点衍生而来。Malantide TFA 是PKA 的高度特异性底物，Km 为 15 μM，并且在各种大鼠组织提取物中显示出 PKI 抑制 > 90％底物磷酸化。Malantide TFA 也是PKC 的有效底物，Km 为 16 μM。

Myelin Basic Protein (MHP4-14) TFA 是一种合成肽，包含髓鞘碱性蛋白的残基4-14，是一种非常有选择性的 PKC 底物 (Km=7 μM)。Myelin Basic Protein TFA 不被环腺苷酸依赖性蛋白激酶、酪蛋白激酶 I 和 II、Ca2+/钙调素依赖性蛋白激酶 II 或磷酸化酶激酶磷酸化，可常规用于测定粗组织提取物中低背景的蛋白激酶 C。