Lack of regulation of aromatic L-amino acid decarboxylase in intact bovine chromaffin cells.
Lack of regulation of aromatic L-amino acid decarboxylase in intact bovine chromaffin cells.
复制标题
完整牛嗜铬细胞中芳香族 L-氨基酸脱羧酶缺乏调节。
DOI：
10.1046/j.1471-4159.2002.00849.x
复制
发表时间：
2002
影响因子：
4.7
通讯作者：
Haycock,JohnW
中科院分区：
文献类型：
--
作者：
Waymire,JackC;Haycock,JohnW
芳香族氨基酸脱羧酶（AADC）是儿茶酚胺生物合成途径中的第二种酶，其活性通常被认为不具有限制性，因此不参与调节通过该途径的通量。最近的研究表明，它的活性可以在体内调节，并且该酶可以在体外磷酸化和活化，这提高了AADC在儿茶酚胺生物合成中可能发挥的不仅仅是一种强制性作用的可能性。在本研究中，在完整的牛嗜铬细胞中，相对于酪氨酸羟化酶（TH;途径中的第一种和限速酶），评估了AADC的磷酸化和活性。用高钾、乙酰胆碱、佛波醇二丁酸酯、毛喉素或冈田酸处理嗜铬细胞，均增加32 P掺入TH（用32 Pi代谢标记ATP库后）和TH活性。与此相反，在匹配的样品中测量，32 P掺入AADC中未检测到，并且没有任何治疗改变AADC活性。因此，AADC能够在体外被磷酸化和激活，其生理学意义值得怀疑。
Aromaticl‐amino acid decarboxylase (AADC) is the second enzyme in the catecholamine biosynthetic pathway, and its activity is generally considered not to be limiting, and therefore not involved, in regulating flux through this pathway. Recent studies showing that its activity can be regulatedin vivoand that the enzyme can be phosphorylated and activatedin vitrohave raised the possibility that AADC may play more than an obligatory role in catecholamine biosynthesis. In the present study, the phosphorylation and activity of AADC was evaluated relative to that of tyrosine hydroxylase (TH; the first and rate‐limiting enzyme in the pathway) in intact bovine chromaffin cells. Treatment of chromaffin cells with elevated potassium, acetylcholine, phorbol dibutyrate, forskolin, or okadaic acid each increased32P incorporation into TH (after metabolic labeling of ATP pools with32Pi) and TH activity. In contrast, as measured in matched samples,32P incorporation into AADC was not detected and none of the treatments altered AADC activity. Thus, that AADC can be phosphorylated and activatedin vitrohas questionable physiological significance.