Mugnaini E, Dahl A L, Morgan J I
Laboratory of Neuromorphology, University of Connecticut, Storrs 06268.
Synapse. 1988;2(2):125-38. doi: 10.1002/syn.890020204.
Cerebellin is a hexadecapeptide that has been biochemically characterized and localized to cerebellar Purkinje cells and certain neurons of the dorsal cochlear nucleus (DCoN) of rat. Among rabbit antisera produced to synthetic cerebellins, one (C1) gave specific immunostaining of the Purkinje neuronal cell body, initial axon segment, and main stem dendrites, while another (R2) reacted with peripheral dendritic structures. This complementarity of staining was also present during cerebellar development. By electron microscopy, the immunoreaction product was localized to polyribosomal domains with antiserum C1 and to dendritic spines with antiserum R2, in both cerebellar cortex and DCoN. In the spine, the structure most strongly stained was the postsynaptic density, but some reaction product was adsorbed to the plasma membrane, the spine apparatus, and the granulofibrillar cytoplasmic component. Antiserum R2 also stained lysosome-like bodies. We suggest that antiserum C1 recognizes cerebellin precursor(s) and antiserum R2 mature peptide(s) and perhaps degradation product. There is structural homology between cerebellin and residues 625-641 of the polyimmunoglobulin transporter. The functional implications of this homology and other possible roles of cerebellin are discussed.
小脑素是一种十六肽，已通过生物化学方法进行了表征，并定位于大鼠小脑浦肯野细胞和背侧耳蜗核（DCoN）的某些神经元。在针对合成小脑素产生的兔抗血清中，一种（C1）对浦肯野神经元细胞体、初始轴突段和主要干树突进行特异性免疫染色，而另一种（R2）与外周树突结构发生反应。这种染色互补性在小脑发育过程中也存在。通过电子显微镜观察，在小脑皮质和DCoN中，免疫反应产物在抗血清C1作用下定位于多核糖体区域，在抗血清R2作用下定位于树突棘。在树突棘中，染色最强的结构是突触后致密部，但一些反应产物吸附在质膜、树突棘器和颗粒纤维状细胞质成分上。抗血清R2还对溶酶体样小体进行染色。我们认为抗血清C1识别小脑素前体，抗血清R2识别成熟肽以及可能的降解产物。小脑素与多聚免疫球蛋白转运体的625 - 641位残基之间存在结构同源性。本文讨论了这种同源性的功能意义以及小脑素的其他可能作用。
