On the identity of the major postsynaptic density protein.
On the identity of the major postsynaptic density protein.
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关于主要突触后密度蛋白的身份。
DOI：
10.1073/pnas.89.7.3015
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发表时间：
1992
影响因子：
11.1
通讯作者：
Black,IB
中科院分区：
文献类型：
--
作者：
Wu,K;Huang,Y;Adler,J;Black,IB
越来越多的证据表明，突触后致密物（PSD）在突触通讯和可塑性中起着重要作用。主要PSD蛋白（mPSDp），钙/钙调蛋白依赖性蛋白激酶，似乎是PSD功能的核心。mPSDp长期以来被认为与可溶性钙调蛋白激酶II（α-CKII）的α亚基相同。然而，mPSDp和α-CKII在溶解性和抗原性方面确实不同，这增加了这两种蛋白质不同的可能性。为了进一步确定这两种蛋白质之间的关系，我们从成年大鼠大脑皮层中纯化mPSDp至同质，并比较蛋白质。与α-CKII相反，纯化的mPSDp不溶于高浓度的盐、各种洗涤剂、二价阳离子的螯合剂和强变性剂盐酸胍。mPSDp的pI值为6.2，而α-CKII的pI值为6.7-7.2。纯化的mPSDp结合钙调素在Ca 2+的存在下，并在Ca 2 +/钙调素依赖性的方式自磷酸化。针对mPSDp的多克隆抗血清（anti-mPSDp）识别纯化的mPSDp或突触膜中的mPSDp，表明突触蛋白之间的免疫特异性。抗mPSDp不识别α-CKII，而抗α-CKII抗体仅与mPSDp微弱反应，表明蛋白质不同但结构相似。此外，蛋白酶V8消化的多肽的序列分析显示，至少有一个8-氨基酸序列，MLKVPNIS，这是不存在于α-CKII。最后，HPLC分析的V8消化片段的mPSDp和α-CKII的平行显示不同的肽模式。因此，我们的观察结果表明，mPSDp和α-CKII是相似的，但不相同。mPSDp独特的物理化学和结构特性可能为介导突触可塑性的分子机制提供见解。
Increasing evidence suggests that the postsynaptic density (PSD) plays a critical role in synaptic communication and plasticity. The major PSD protein (mPSDp), a calcium/calmodulin-dependent protein kinase, appears to be central to PSD function. The mPSDp has long been considered identical to the alpha subunit of the soluble calmodulin kinase II (alpha-CKII). However, mPSDp and alpha-CKII do differ in solubility and antigenicity, raising the possibility that the two proteins are distinct. To further define the relationship between the two proteins, we purified the mPSDp to homogeneity from adult rat cerebral cortex and compared the proteins. In contrast to alpha-CKII, the purified mPSDp was insoluble in high concentrations of salt, various detergents, chelators of divalent cations, and the strong denaturant guanidine hydrochloride. The pI value of the mPSDp was 6.2, whereas that of alpha-CKII was 6.7-7.2. The purified mPSDp bound calmodulin in the presence of Ca2+ and was autophosphorylated in a Ca2+/calmodulin-dependent manner. Polyclonal antiserum raised against mPSDp (anti-mPSDp) recognized purified mPSDp or mPSDp in synaptic membrane, indicating immunologic specificity among the synaptic proteins. Anti-mPSDp did not recognize alpha-CKII, whereas anti-alpha-CKII antibodies reacted only weakly with mPSDp, suggesting that the proteins are distinct but structurally similar. Moreover, sequence analysis of protease V8-digested polypeptides revealed that there was at least an 8-amino acid sequence, MLKVPNIS, that is not present in alpha-CKII. Finally, HPLC analysis of V8-digested fragments of mPSDp and alpha-CKII in parallel revealed dissimilar peptide patterns. Thus our observations suggest that mPSDp and alpha-CKII are similar but not identical. The unique physicochemical and structural properties of the mPSDp may provide insights into molecular mechanisms mediating synaptic plasticity.