Connor K, Clegg R A
Hannah Research Institute, Ayr, Scotland, U.K.
Biochem J. 1993 May 1;291 ( Pt 3)(Pt 3):817-24. doi: 10.1042/bj2910817.
Protein kinase isoenzymes belonging to the protein kinase C (PK-C) family present in rat mammary tissue have been resolved from one another by chromatography on hydroxyapatite, and characterized. PK-C alpha is the predominant isoenzyme and is present at a constant level of activity throughout mammary-gland development and differentiation. In contrast, marked changes in the relative abundance of other mammary PK-C isoenzymes accompany the transition from pregnancy to lactation. The sensitivity of mammary PK-C alpha to Ca2+ is greater in tissue from pregnant than from lactating rats. This isoenzyme has other atypical properties consistent with its being more highly phosphorylated than PK-C alpha in rat brain and spleen. One of the protein kinase isoenzymes resolved from mammary tissue recognizes the peptide substrate used to assay AMP-activated kinase and may thus interfere in the determination of this activity. Another is fully active in the absence of Ca2+ and is more than 80% active in the absence of added lipid effectors. A 'housekeeping' role is proposed for PK-C alpha in mammary tissue, whereas the less abundant PK-C isoenzymes may be involved in mammary cell proliferation and differentiation.
通过羟基磷灰石层析法，已将大鼠乳腺组织中存在的属于蛋白激酶C（PK-C）家族的蛋白激酶同工酶彼此分离并进行了表征。PK-Cα是主要的同工酶，在整个乳腺发育和分化过程中，其活性水平保持恒定。相比之下，从妊娠到泌乳的转变伴随着其他乳腺PK-C同工酶相对丰度的显著变化。妊娠大鼠组织中乳腺PK-Cα对Ca2+的敏感性高于泌乳大鼠。这种同工酶具有其他非典型特性，这与其在大鼠脑和脾脏中比PK-Cα磷酸化程度更高是一致的。从乳腺组织中分离出的一种蛋白激酶同工酶可识别用于检测AMP激活激酶的肽底物，因此可能会干扰该活性的测定。另一种在没有Ca2+的情况下完全有活性，在没有添加脂质效应物的情况下活性超过80%。有人提出PK-Cα在乳腺组织中起“管家”作用，而含量较少的PK-C同工酶可能参与乳腺细胞的增殖和分化。
