fibronectin 与gelatin的区别

baichunyu

诸位，谁了解fibronectin 与gelatin二者有什么区别呢？请赐教！

chinajinlei

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Fibronectin is a high-molecular weight (~440kDa) extracellular matrix glycoprotein that binds to membrane-spanning receptor proteins called integrins.[1] In addition to integrins, fibronectin also binds extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans (e.g. syndecans).- u0 s. A& Y" o) \
    Fibronectin exists as a dimer, consisting of two nearly identical monomers linked by a pair of disulfide bonds.[1] The fibronectin protein is produced from a single gene, but alternative splicing of its pre-mRNA leads to the creation of several isoforms.7 o/ {% g1 N/ T& J$ u( m
    Two types of fibronectin are present in vertebrates:
! f: n1 a; O$ [    (1)Soluble plasma fibronectin (formerly called "cold-insoluble globulin", or CIg) is a major protein component of blood plasma (300 μg/ml) and is produced in the liver by hepatocytes. 1 s6 |. O7 k* f, C- d. C
    (2)Insoluble cellular fibronectin is a major component of the extracellular matrix. It is secreted by various cells, primarily fibroblasts, as a soluble dimer and is then assembled into an insoluble matrix in a complex cell-mediated process. ; G+ E8 v9 s4 x6 u* Z
  Fibronectin plays a major role in cell adhesion, growth, migration and differentiation, and it is important for processes such as wound healing and embryonic development. Altered fibronectin expression, degradation, and organization has been associated with a number of pathologies, including cancer and fibrosis.9 _# c4 [4 x% b* n! R

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    Gelatin (spelled gelatine in some Commonwealth countries, from the French gélatine) is a translucent, colorless, brittle (when dry), nearly tasteless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar way are called gelatinous. Gelatin is an irreversibly hydrolysed form of collagen, and is classified as a foodstuff, with E number E441. It is found in some gummy candies as well as other products such as marshmallows, gelatin dessert, and some low-fat yogurt. Household gelatin comes in the form of sheets, granules, or powder. Instant types can be added to the food as they are; others need to be soaked in water beforehand. Some dietary or religious customs forbid the use of gelatin from certain animal sources, and medical issues may limit or prevent its consumption by certain people. Many vegetarians and vegans also abstain from eating gelatin.2 ^' _% }: L* `0 I. J
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References
; B3 M: O0 u6 u9 x! Z: u! i( c2 |http://en.wikipedia.org/wiki/Fibronectin0 c* i$ f4 m  s1 k
http://en.wikipedia.org/wiki/Gelatin, {5 y8 v( [: S  \

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      细胞外基质的组成可分为三大类：
* w. S: u$ K3 `  C①糖胺聚糖(glycosaminoglycans)、蛋白聚糖(proteoglycan),它们能够形成水性细胞外基质的胶状物，在这种胶状物中包埋有许多其它的基质成分；
5 x6 n0 h" [1 s- A: L②结构蛋白，如胶原和弹性蛋白，它们赋予细胞外基质一定的强度和韧性；
  B* H" S' T, q③粘着蛋白(adhesive)：如纤粘连蛋白和层粘联蛋白，它们促使细胞同基质结合。0 W2 q9 }# ]  q% _/ r+ L, y7 P: H' ~
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      胶原(Collagen)和纤粘连蛋白(fibronectin，FN)都是细胞外基质的组成部分。
: ]5 Q. N9 z! g# A+ s1 `      明胶(Gelatin)是胶原(Collagen)的水解产物，由于失去了胶原在体内的三维结构，明胶已经完全不具有生物活性，没有修复作用，不能成膜。由于明胶中含有RGD生物活性短肽, 有利于细胞表面粘附分子识别。
! E- G. R  {' o# Y! M（胶原是细胞外基质中的主要框架结构。目前发现的胶原至少19种。每种胶原的结构特性均与其特定功能相适应。可形成胶原纤维(Ⅰ、Ⅱ、Ⅲ型)、三维网络结构(Ⅳ型)的片层胶原。）
" H0 @' W3 c7 g  l5 a      纤粘连蛋白(fibronectin，FN)分血浆FN和细胞FN。血浆FN存在于血浆及各种体液中；细胞FN存在于细胞外基质(包括某些基膜)及细胞表面。FN的功能：主要是介导细胞粘着，以此调节细胞形状和细胞骨架的组装，促进细胞铺展、迁移，并可通过迁移途径决定细胞的分化方向。
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参考文献：! V# {7 Z7 ]) }, b* }3 U
[1] 范宏斌, 胡蕴玉, 吴红等. 转化生长因子明胶微球制备及体外缓释研究. 中国矫形外科杂志, 2005, 13(3):208-211
5 j3 O  ^, g( y- ]% n[2] 关林波, 但卫华, 曾睿等. 明胶及其在生物材料中的应用. 材料导报, 2006, 2O(Ⅶ):380-383