Chernik Ivan S, Seit-Nebi Alim S, Marston Steven B, Gusev Nikolai B
Department of Biochemistry, School of Biology, Moscow State University, Moscow, 119992, Russia.
Mol Cell Biochem. 2007 Jan;295(1-2):9-17. doi: 10.1007/s11010-006-9266-8. Epub 2006 Nov 16.
Interaction of human 14-3-3gamma with the small heat shock protein Hsp20 was analyzed by means of size-exclusion chromatography and chemical crosslinking. Unphosphorylated Hsp20 and its mutant S16D mimicking phosphorylation by cAMP-dependent protein kinase did not interact with 14-3-3. Phosphorylated Hsp20 formed a tight complex with 14-3-3 in which dimer of 14-3-3 was bound to dimer of Hsp20. 14-3-3 did not affect the chaperone activity of unphosphorylated Hsp20 but increased the chaperone activity of phosphorylated Hsp20 if insulin was used as a model substrate. Estimation of the effect of 14-3-3 on the chaperone activity of Hsp20 with other model substrates was complicated by the fact that under in vitro conditions isolated 14-3-3 possessed its own high chaperone activity. Taken into account high content of Hsp20 in different muscles it is supposed that upon phosphorylation Hsp20 might effectively compete with multiple protein targets of 14-3-3 and by this means indirectly affect many intracellular processes.
通过尺寸排阻色谱法和化学交联法分析了人14-3-3γ与小热休克蛋白Hsp20的相互作用。未磷酸化的Hsp20及其模拟cAMP依赖性蛋白激酶磷酸化的突变体S16D不与14-3-3相互作用。磷酸化的Hsp20与14-3-3形成紧密复合物，其中14-3-3的二聚体与Hsp20的二聚体结合。如果以胰岛素作为模型底物，14-3-3不影响未磷酸化Hsp20的伴侣活性，但会增加磷酸化Hsp20的伴侣活性。由于在体外条件下分离的14-3-3自身具有较高的伴侣活性，因此评估其对Hsp20与其他模型底物的伴侣活性的影响较为复杂。考虑到不同肌肉中Hsp20的含量较高，推测磷酸化后的Hsp20可能有效地与14-3-3的多个蛋白质靶点竞争，并通过这种方式间接影响许多细胞内过程。
