Cell juctions

cell junctions总览👇
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anchoring junctions

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接头蛋白连着外面的adhesion protein
anchoring junctions总览👇
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cell-cell

Adhesion belt 黏合带

Function → Coordinated contraction of this network provides the motile活动的 force for a fundamental process in animal morphogenesis形态变化

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Desmosome

Functions → Provide mechanical strength ( eg.heart muscle and the epidermis)

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cell-matrix

Focal adhesion

Functions → Anchor cells to ECM, respond to mechanical forces.

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Hemidemosome

Functions → Anchor cells to the basal lamina基底层

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tight junctions

Tight junctions form a seal between cells and a fence between plasma membrane domains.

structure

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Function

  1. Sealing function → seal adjacent相邻 cells together so that molecules cannot leak freely across the cell sheet.
    防止东西从细胞中间漏过去,比如血脑屏障

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  1. “Fence” function → help maintain the structurally polarized status of epithelia上皮 by preventing apical顶端 or basolateral基底外侧 proteins from diffusing into the wrong region.
    控制转运蛋白位置,注意下图两种转运蛋白

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gap junctions

Gap junctions bridge gaps between adjacent cells so as to create direct channels from the cytoplasm of one to that of the other
在相邻的细胞间形成通道可以从一个细胞质之大另一个细胞质

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Gap junctions are present in most animal tissues
比如connective tissues, epithelia上皮, heart muscle

允许交换无机离子还有一些水溶性小分子

Electrical coupling and metabolic coupling
电耦合和代谢耦合
电耦合指的是交换带电离子,比如电突触
代谢耦合指的是交换代谢产物和营养物

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Cell adhesion molecules 细胞黏附分子

interact in 3 ways👇
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可以分为4个families👇
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Cadherins 钙黏着蛋白

homophilic adhesion
Ca2+ dependent

分类👇
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结构👇hinge domain把它们连在一起,cadherin domain可以和另一条上的结合
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两栖动物胚胎中,cadherin丰富的会聚集在中间,不丰富的会到外面,形成不同的层👇
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Cadherin-dependent cell-cell adhesion guides the organization of developing tissues, and epithelial-mesenchymal transitions (EMT)👇
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Selectins 选择素蛋白

hectorphilic adhesion
Ca2+ dependent

头上有一个lectin凝集素,可以结合细胞表面的糖👇
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主要是在血管中介导一个暂时的细胞间adhesion,可以招募中性粒细胞去需要的组织👇
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Integrins 整联蛋白

heterophilic adhesion

Ca2+ and Mg2+ dependent

有α β两个亚基,可以通过构型变换开关👇
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Link the ECM to the cytoskeleton and transmit signals in both directions

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Adhesive immunoglobulin (Ig) superfamily members 黏附免疫球蛋白超家族

both heterophilic adhesion and homophilic adhesion

Ca2+ independent

Contain one or more extracellular Ig-like domains that are characteristic of antibody molecules👇
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