CROSS-LINKING OF DARK-ADAPTED FROG PHOTORECEPTOR DISK MEMBRANES - EVIDENCE FOR MONOMERIC RHODOPSIN
CROSS-LINKING OF DARK-ADAPTED FROG PHOTORECEPTOR DISK MEMBRANES - EVIDENCE FOR MONOMERIC RHODOPSIN
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DOI：
10.1016/s0006-3495(85)83918-7
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发表时间：
1985-01-01
影响因子：
3.4
通讯作者：
DOWNER, NW
中科院分区：
文献类型：
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作者：
DOWNER, NW
一个模型的随机交联相同的单体扩散在膜中制定测试视紫红质的交联行为是否是定量一致的单体结构。使用试剂戊二醛对完整视网膜和分离的视杆细胞外段（ROS）膜中的视紫红质进行交联。通过SDS[十二烷基硫酸钠]-聚丙烯酰胺凝胶电泳分析形成的共价低聚物的分布，并与随机模型的预测进行比较。对由二异氰酸酯基己烷交联的ROS膜和由与邻菲咯啉络合的Cu离子交联的视网膜进行了类似的分析。由这3种试剂产生的交联模式与单体模型相当一致。戊二醛也用于交联四聚体蛋白质醛缩酶，以验证在与用于ROS的条件相当的条件下，稳定的寡聚体的交联产生具有D2对称性的四聚体蛋白质的预测模式。这种模式与随机碰撞模型的模式明显不同。速率的比较表明，与戊二醛的醛缩酶交联明显快于膜结合的视紫红质的交联。显然，视紫红质在暗适应感光膜中是单体，并且观察到的交联是由扩散的视紫红质分子之间的碰撞引起的。
A model for random cross-linking of identical monomers diffusing in a membrane was formulated to test whether rhodopsin''s cross-linking behavior was quantitatively consistent with a monomeric structure. Cross-linking was performed on rhodopsin both in intact retinas and in isolated rod outer segment (ROS) membranes using the reagent glutaraldehyde. The distribution of covalent oligomers formed was analyzed by SDS[sodium dodecylsulfate]-polyacrylamide gel electrophoresis and compared to predictions for the random model. A similar analysis was made for ROS membranes cross-linked by diisocyanatohexane and retinas cross-linked by Cu ion complexed with o-phenanthroline. Patterns of cross-linking produced by these 3 reagents are reasonably consistent with the monomer model. Glutaraldehyde was also used to cross-link the tetrameric protein aldolase in order to verify that cross-linking of a stable oligomer, under conditions comparable to those used for ROS, yielded the pattern predicted for a tetrameric protein having D2 symmetry. This pattern is markedly different from the one for a random-collision model. A comparison of rates showed that aldolase cross-linking with glutaraldehyde is significantly faster than cross-linking of membrane-bound rhodopsin. Apparently, rhodopsin is monomeric in dark-adapted photoreceptor membranes and that the observed cross-linking results from collisions between diffusing rhodopsin molecules.