Meyer H E, Meyer G F, Dirks H, Heilmeyer L M
Abteilung für Biochemie Supramolekularer Systeme, Ruhr-Universität Bochum, Federal Republic of Germany.
Eur J Biochem. 1990 Mar 10;188(2):367-76. doi: 10.1111/j.1432-1033.1990.tb15413.x.
The alpha subunit of skeletal muscle phosphorylase kinase, as isolated, carries phosphate at the serine residues 1018, 1020 and 1023. Employing the S-ethyl-cysteine method, these residues are found to be phosphorylated partially, i.e. differently phosphorylated species exist in muscle. Serine 1018 is a site which can be phosphorylated by the cyclic-AMP-dependent protein kinase. The serine residues 972, 985 and 1007 are phosphorylated by phosphorylase kinase itself when its activity is stimulated by micromolar concentrations of Ca2+. These phosphorylation sites are not identical to those found to be phosphorylated already in the enzyme as prepared from freshly excised muscle. A 'multiphosphorylation loop' uniquely present in this but not in the homologous beta subunit contains all the phosphoserine residues so far identified in the alpha subunit.
骨骼肌磷酸化酶激酶的α亚基在分离时，其丝氨酸残基1018、1020和1023上带有磷酸基团。采用S-乙基半胱氨酸方法发现，这些残基只是部分磷酸化，即肌肉中存在不同磷酸化状态的物种。丝氨酸1018是一个可被环磷酸腺苷依赖性蛋白激酶磷酸化的位点。当微摩尔浓度的Ca2+刺激其活性时，丝氨酸残基972、985和1007会被磷酸化酶激酶自身磷酸化。这些磷酸化位点与从新鲜切除的肌肉中制备的酶中已发现的磷酸化位点不同。一个仅存在于该α亚基而非同源β亚基中的“多磷酸化环”包含了迄今为止在α亚基中鉴定出的所有磷酸丝氨酸残基。
