Phosphorylation of the immunosuppressant FK506-binding protein FKBP52 by casein kinase II: Regulation of HSP90-binding activity of FKBP52
Phosphorylation of the immunosuppressant FK506-binding protein FKBP52 by casein kinase II: Regulation of HSP90-binding activity of FKBP52
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DOI：
10.1073/pnas.94.26.14500
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发表时间：
1997-12-23
影响因子：
11.1
通讯作者：
Baulieu, EE
中科院分区：
文献类型：
--
作者：
Miyata, Y;Chambraud, B;Baulieu, EE
FKBP52 （HSP56, p59， HBT）是59 kda的免疫抑制剂fk506结合蛋白，在体外具有肽基脯氨酸异构酶和伴侣样活性。FKBP52与热休克蛋白HSP90相关，存在于体内类固醇激素受体复合物中。FKBP52具有一个保守的酪蛋白激酶II （CK2）磷酸化位点，该位点先前被证明与HSP90相关。我们在体内和体外检测了FKBP52是否被CK2磷酸化，重组兔FKBP52被纯化的CK2磷酸化。我们表达并纯化了FKBP52的缺失突变体，以确定CK2磷酸化的位点。铰链I区的Thr-143被确定为CK2的主要磷酸化位点。与该区域对应的合成肽被CK2磷酸化，并且该肽竞争性地抑制CK2对其他底物的磷酸化。对表达FKBP52的细胞进行[P-32]磷酸标记，发现体内同一位点也被磷酸化，FK506结合FKBP52不影响CK2的磷酸化，相反，FKBP52的FK506结合活性不受磷酸化的影响。最重要的是，CK2磷酸化的FKBP52不与HSP90结合，这些结果表明CK2在体外和体内都能磷酸化FKBP52，从而可能调节含有伴侣复合物的蛋白质组成，如类固醇受体和某些蛋白激酶的蛋白质组成。
FKBP52 (HSP56, p59, HBT) is the 59-kDa immunosuppressant FK506-binding protein and has peptidyl prolyl isomerase as well as a chaperone-like activity in vitro. FKBP52 associates with the heat shock protein HSP90 and is included in the steroid hormone receptor complexes in vivo. FKBP52 possesses a well conserved phosphorylation site for casein kinase II (CK2) that was previously shown to be associated with HSP90. Here,ve examined whether FKBP52 is phosphorylated by CK2 both in vivo and in vitro, Recombinant rabbit FKBP52 was phosphorylated by purified CK2. We expressed and purified deletion mutants of FKBP52 to determine the site(s) phosphorylated by CK2. Thr-143 in the hinge I region was identified as the major phosphorylation site for CK2. A synthetic peptide corresponding to this region was phosphorylated by CK2, and the peptide competitively inhibited the phosphorylation of other substrates by CK2. The [P-32] phosphate labeling of FKBP52-expressing cells revealed that the same site is also phosphorylated in vivo, FK506 binding to FKBP52 did not affect the phosphorylation by CK2 and, conversely, the FK506 binding activity of FKBP52 was not affected by the phosphorylation. Most importantly, CK2-phosphorylated FKBP52 did not bind to HSP90, These results indicate that CK2 phosphorylates FKBP52 both in vitro and in vivo and thus may regulate the protein composition of chaperone-containing complexes such as those of steroid receptors and certain protein kinases.