細胞膜和細胞表面ppt課件(編輯修改稿)
2025-05-31 12:01 本頁面
【文章內(nèi)容簡介】 a protein found in the membrane of certain photosynthetic bacteria, illustrates the general structure of all these proteins 細菌視紫質(zhì)結(jié)構(gòu)模型 離子通道也是多次跨膜蛋白家族 ? 鉀離子通道由四聚體構(gòu)成，每個亞單位有一對跨膜螺旋，螺旋的方向改變調(diào)節(jié)離子的流動。 ? Ion channels pose a second large and important family of multipass transmembrane proteins. As revealed by the crystal structure of a resting K+ channel, ion channels are typically tetrameric proteins. Each of the four subunits has a pair of membranespanning helices that bundle with helices of other subunits, forming a central channel Multiple β Strands in Porins Form embraneSpanning “Barrels ? 革蘭氏陰性細菌外膜中孔道蛋白，可以小分子親水物質(zhì)進出，防止對細菌有害的進入。 ? The porins are a class of transmembrane proteins whose structure differs radically from that of other integral proteins. Several types of porin are found in the outer membrane of gramnegative bacteria such as E. coli and in the outer membranes of mitochondria and chloroplasts. The outer membrane protects an intestinal bacterium from harmful agents (., antibiotics, bile salts, and proteases) but permits the uptake and disposal of small hydrophilic molecules including nutrients and waste products. The porins in the outer membrane of an E. coli cell provide channels for the passage of disaccharides and other small molecules as well as phosphate. 去垢劑 detergent ? 去垢劑是一端親水、另一端疏水的兩性小分子 ,是分離與研究膜蛋白的常用試劑。 ? 離子型去垢劑 (SDS)和非離子型去垢劑（ Triton X100） ? SDS: CH3(CH2)11OSO3Na+ 細胞膜和細胞骨架相互影響 Interactions with the Cytoskeleton Impede the Mobility of Integral Membrane Proteins 與蛋白在人工脂質(zhì)體上的表現(xiàn)不同，在活細胞里，蛋白的移動速率要低的多 1/1030 。 However, the diffusion rate of a protein in the plasma membrane of intact cells is generally 10–30 times lower than that of the same protein embedded in synthetic spherical bilayer structures (liposomes). These findings suggest that the mobility of integral proteins in the plasma membrane of living cells is restricted by interactions with the rigid submembrane cytoskeleton. 生物膜一些概念 ? 單位膜 ? 流動鑲嵌模型 細胞連接 Cell–Cell and Cell–Matrix Adhesion,INTEGRATING CELLS INTO TISSUES ? 細胞通過細胞粘連分子相互連接 ? Cells in tissues can adhere directly to one another (cell–cell adhesion) through specialized integral membrane proteins called celladhesion molecules (CAMs) that often cluster into specialized cell junctions celladhesion molecules (CAMs) ? 細胞黏連分子分成鈣黏素，免疫球蛋白超家族，整合素，選擇素。 ? 其他參加細胞粘連的膜蛋白 ? A large number of CAMs
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