Position of rhodopsin photoisomerization on the disk surface confers variability to the rising phase of the single photon response in vertebrate rod photoreceptors.
Position of rhodopsin photoisomerization on the disk surface confers variability to the rising phase of the single photon response in vertebrate rod photoreceptors.
复制标题
DOI：
10.1371/journal.pone.0240527
复制
发表时间：
2020
期刊：
影响因子：
3.7
通讯作者：
DiBenedetto E
中科院分区：
文献类型：
--
作者：
Caruso G;Klaus CJ;Hamm HE;Gurevich VV;Makino CL;DiBenedetto E
视网膜杆的功能是精确的光子计数器，以提供在非常昏暗的光线下的视觉。要做到这一点，杆必须产生高度放大的，可重复的响应单光子，但外部段的架构和随机性的位置视紫红质光异构化的表面上的内部磁盘的光子响应的上升阶段引入可变性。在椎间盘边缘发生光异构化后不久，质膜附近cGMP的耗尽关闭离子通道并使杆超极化。但是在圆盘中心的光异构化，cGMP的局部消耗远离质膜中的通道。因此，通道关闭被cGMP浓度降低到达质膜所需的时间延迟。此外，cGMP的局部下降在影响通道之前消散在更大的体积上，因此响应幅度降低。这种变异性的来源随着圆盘半径的增加而增加。使用一个完全空间分辨的生物物理模型杆光转导，我们量化的可变性可归因于随机性的光异构化的位置作为磁盘结构的函数。在具有承载单个增量的小圆盘的小鼠杆中，在没有增量的情况下，这种变异性可以忽略不计。变异性略有增加的increased，但在关闭视紫红质的随机性出现的主要来源，单光子响应的变化，但在所有的最早的时间。光异构化的横向位置的随机性所产生的变化增加的幅度，并坚持在一个较长的时间内在大蝾螈棒的光子响应。蝾螈杆盘中的多个切口的对称布置大大降低了这种变化在上升阶段，但切口有相反的效果所产生的随机性在视紫红质关闭在以后的时间的变化。
Retinal rods function as accurate photon counters to provide for vision under very dim light. To do so, rods must generate highly amplified, reproducible responses to single photons, yet outer segment architecture and randomness in the location of rhodopsin photoisomerization on the surface of an internal disk introduce variability to the rising phase of the photon response. Soon after a photoisomerization at a disk rim, depletion of cGMP near the plasma membrane closes ion channels and hyperpolarizes the rod. But with a photoisomerization in the center of a disk, local depletion of cGMP is distant from the channels in the plasma membrane. Thus, channel closure is delayed by the time required for the reduction of cGMP concentration to reach the plasma membrane. Moreover, the local fall in cGMP dissipates over a larger volume before affecting the channels, so response amplitude is reduced. This source of variability increases with disk radius. Using a fully space-resolved biophysical model of rod phototransduction, we quantified the variability attributable to randomness in the location of photoisomerization as a function of disk structure. In mouse rods that have small disks bearing a single incisure, this variability was negligible in the absence of the incisure. Variability was increased slightly by the incisure, but randomness in the shutoff of rhodopsin emerged as the main source of single photon response variability at all but the earliest times. Variability arising from randomness in the transverse location of photoisomerization increased in magnitude and persisted over a longer period in the photon response of large salamander rods. A symmetric arrangement of multiple incisures in the disks of salamander rods greatly reduced this variability during the rising phase, but the incisures had the opposite effect on variability arising from randomness in rhodopsin shutoff at later times.
登录
查看更多内容
影响因子：
4.8
作者：
Bayburt, Timothy H.;Vishnivetskiy, Sergey A.;Gurevich, Vsevolod V.
通讯作者：
Gurevich, Vsevolod V.
DOI：
10.1523/jneurosci.0819-09.2009
发表时间：
2009-09-23
期刊：
The Journal of neuroscience : the official journal of the Society for Neuroscience
影响因子：
--
作者：
Doan T;Azevedo AW;Hurley JB;Rieke F
通讯作者：
Rieke F
影响因子：
2.5
作者：
BORGES, S;WILSON, M
通讯作者：
WILSON, M
影响因子：
64.8
作者：
Fotiadis, D;Liang, Y;Palczewski, K
通讯作者：
Palczewski, K
影响因子：
4.3
作者：
Caruso G;Bisegna P;Lenoci L;Andreucci D;Gurevich VV;Hamm HE;DiBenedetto E
通讯作者：
DiBenedetto E