THE PHOSPHORYLATION TARGETS OF P47(PHOX), A SUBUNIT OF THE RESPIRATORY BURST OXIDASE - FUNCTIONS OF THE INDIVIDUAL TARGET SERINES AS EVALUATED BY SITE-DIRECTED MUTAGENESIS
THE PHOSPHORYLATION TARGETS OF P47(PHOX), A SUBUNIT OF THE RESPIRATORY BURST OXIDASE - FUNCTIONS OF THE INDIVIDUAL TARGET SERINES AS EVALUATED BY SITE-DIRECTED MUTAGENESIS
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DOI：
10.1172/jci118187
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发表时间：
1995-09-01
影响因子：
15.9
通讯作者：
CHANOCK, SJ
中科院分区：
文献类型：
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作者：
FAUST, LP;ELBENNA, J;CHANOCK, SJ
吞噬细胞和B淋巴细胞的呼吸爆发氧化酶催化氧气以NADPH为代价还原为O-2（-）。在休眠细胞中，氧化酶通过将细胞暴露于适当的刺激而被激活。在活化过程中，p47（phox），一种细胞溶质氧化酶亚基，在位于S303-S379之间的许多丝氨酸上广泛磷酸化。为了确定这种磷酸化是否是氧化酶激活所必需的，我们检测了用表达p47（phox）的各种S -> A突变体的质粒转染后，在p47（phox）缺陷的EBV转化的B淋巴母细胞中佛波醇引起的氧化酶活性。含有S -> A突变的突变体涉及S303和S379之间的所有丝氨酸[S（303-379）A]，在活化过程中不磷酸化，不易位到质膜，并且几乎没有功能。S379是特别感兴趣的，因为（a）p47（phox）S379在表达野生型p47（phox）的佛波醇活化的淋巴母细胞中被磷酸化，和（B）p47（phox）S379 A未能转移到膜上，并且与p47（phox）S（303-379）A一样无功能;其他单个S --> A突变对氧化酶活性影响不大。这些发现表明，磷酸化的S379可能是重要的氧化酶在整个细胞中的激活。
The respiratory burst oxidase of phagocytes and B lymphocytes catalyzes the reduction of oxygen to O-2(-) at the expense of NADPH. Dormant in resting cells, the oxidase is activated by exposing the cells to appropriate stimuli. During activation, p47(phox), a cytosolic oxidase subunit, becomes extensively phosphorylated on a number of serines located between S303-S379. To determine whether this phosphorylation is necessary for oxidase activation, we examined phorbol-elicited oxidase activity in EBV-transformed B lymphoblasts deficient in p47(phox) after transfection with plasmids expressing various S --> A mutants of p47(phox). The mutant containing S --> A mutations involving all serines between S303 and S379 [S(303-379) A] was not phosphorylated, did not translocate to plasma membrane during activation and was almost devoid of function, As to individual serines, S379 was of special interest because (a) p47(phox) S379 was phosphorylated in phorbol-activated lymphoblasts expressing wild-type p47(phox), and (b) p47(phox) S379A failed to translocate to the membrane, and was as functionless as p47(phox) S(303-379) A; other single S --> A mutations had little effect on oxidase activity. These findings suggest that the phosphorylation of S379 may be important for oxidase activation in whole cells.