Restrictions on rotational and translational diffusion of pigment in the membranes of a rhabdomeric photoreceptor.
Restrictions on rotational and translational diffusion of pigment in the membranes of a rhabdomeric photoreceptor.
复制标题
对横纹肌感光器的膜中色素旋转和翻译扩散的限制。
DOI：
10.1085/jgp.70.4.453
复制
发表时间：
1977-10
影响因子：
3.8
通讯作者：
Wehner, R
中科院分区：
文献类型：
--
作者：
Goldsmith, T H;Wehner, R
个体，孤立的横纹肌从黑暗适应的小龙虾（Orconectes，Procambarus）进行了研究与横向入射微束，可以放置在单个堆栈的微绒毛。沿着微绒毛的长度的metarhodopsin的浓度梯度产生的局部漂白剂，完成了在pH 9的戊二醛或甲醛的存在下，用小斑点的橙子光照射。在黑暗中没有观察到随后的色素再分布，表明没有平移扩散。根据与其他系统的比较，预期戊二醛而非甲醛（0.75%）可防止蛋白质在膜中扩散。在相同的条件下，观察到光二色性，表明没有自由布朗旋转。戊二醛中的光二色性大于甲醛中的光二色性，这表明双功能试剂使用甲醛处理后存在的一些分子运动平静。光二色性与数学模型的定量比较表明，颜料吸收矢量在微绒毛轴的+/-50度内对齐，并且以约20度的平均值倾斜到膜的表面中。视紫红质到变视紫红质的光转换伴随着在λ max处摩尔消光增加约20%，并且吸收矢量重新取向几度。过渡力矩或者进一步倾斜到膜中，或者失去其一些轴向取向，或者两者兼而有之。甲醛中的取向变化是戊二醛中的3.5倍。
Individual, isolated rhabdoms from dark-adapted crayfish (Orconectes, Procambarus) were studied with a laterally incident microbeam that could be placed in single stacks of microvilli. Concentration gradients of metarhodopsin along the lengths of microvilli were produced by local bleaches, accomplished by irradiation with small spots of orange light at pH 9 in the presence of glutaraldehyde or formaldehyde. No subsequent redistribution of pigment was observed in the dark, indicating an absence of translational diffusion. On the basis of comparison with other systems, glutaraldehyde, but not formaldehyde (0.75%), would be expected to prevent diffusion of protein in the membrane. Under the same conditions photodichroism is observed, indicating an absence of free Brownian rotation. Photodichroism is larger in glutaraldehyde than in formaldehyde, suggesting that the bifunctional reagent quiets some molecular motion that is present after treatment with formaldehyde. Quantitative comparison of photodichroism with mathematical models indicates that the pigment absorption vectors are aligned within +/- 50 degrees of the microvillar axes and are tilted into the surface of the membrane at an average value of about 20 degrees. The photoconversion of rhodopsin to metarhodopsin is accompanied by an increase in molar extinction of about 20% at the lambda maxand a reorientation of the absorption vector by several degrees. The transition moment either tilts further into the membrane or loses some of its axial orientation, or both. The change in orientation is 3.5 time larger in formaldehyde than in glutaraldehyde.