Sahyoun N, LeVine H, McDonald O B, Cuatrecasas P
J Biol Chem. 1986 Sep 15;261(26):12339-44.
Cytoskeletal interactions which contribute to the assembly of the postsynaptic density (PSD) were investigated. PSDs bound 125I-tubulin specifically with an apparent Km of 2 X 10(-7) M and a Bmax of about 1 nmol/mg of protein. 125I-Tubulin blots revealed that a group of polypeptides between Mr 135,000 and 147,000 (P-140) was a major tubulin-binding PSD component. The P-140 polypeptides were highly enriched in the PSD fraction of purified synaptosomes and could not be detected in crude brain cytoplasm preparations. These polypeptides were subject to phosphorylation by endogenous calmodulin-dependent protein kinase type II, with a concomitant reduction in 125I-tubulin binding. The tubulin-binding polypeptides could also associate with the radiolabeled alpha- and beta-subunits of the calmodulin-dependent protein kinase. These observations are consistent with a role for the P-140 polypeptides in organizing the molecular structure of the PSD. The data also suggest that this structure may be modified by Ca2+-sensitive phosphorylation, thus permitting neuronal activity to modulate the cytoskeletal interactions of the PSD.
对有助于突触后致密区（PSD）组装的细胞骨架相互作用进行了研究。PSD与125I-微管蛋白特异性结合，其表观Km为2×10（-7）M，Bmax约为1 nmol/mg蛋白质。125I-微管蛋白印迹显示，一组分子量在135,000至147,000之间的多肽（P-140）是主要的微管蛋白结合PSD成分。P-140多肽在纯化突触小体的PSD组分中高度富集，在粗制脑细胞质制剂中无法检测到。这些多肽可被内源性钙调蛋白依赖性蛋白激酶II型磷酸化，同时125I-微管蛋白结合减少。微管蛋白结合多肽还可与钙调蛋白依赖性蛋白激酶的放射性标记α和β亚基结合。这些观察结果与P-140多肽在组织PSD分子结构中的作用一致。数据还表明，这种结构可能会被Ca2+敏感的磷酸化修饰，从而使神经元活动能够调节PSD的细胞骨架相互作用。
