Acidic bone matrix proteins and their roles in calcification
Acidic bone matrix proteins and their roles in calcification
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DOI：
10.2741/4026
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发表时间：
2012-01-01
影响因子：
3.1
通讯作者：
Tamura, Masato
中科院分区：
文献类型：
--
作者：
Fujisawa, Ryuichi;Tamura, Masato
哺乳动物的骨骼由蛋白质基质中的磷酸钙晶体组成。磷酸钙的主要形式是羟基磷灰石。骨中最丰富的基质蛋白是I型胶原。胶原蛋白有助于骨的机械性能，并且是组织钙化所必需的。除了胶原蛋白，还有几种酸性蛋白质作为次要成分存在。骨钙素是一种含有γ-羧基谷氨酸的骨蛋白，它对羟基磷灰石有亲和力，可以阻止晶体生长。骨唾液酸蛋白（BSP）和骨桥蛋白是骨的酸性糖磷蛋白。这些蛋白质具有RGD细胞附着序列和酸性氨基酸的连续序列。BSP的聚谷氨酸序列作为羟基磷灰石晶体的可能的成核位点。牙本质磷蛋白是牙本质的主要非胶原蛋白。该蛋白具有（Asp-Ser-Ser）重复序列，其中大部分Ser残基被磷酸化。这些酸性基质蛋白中的一些固定在胶原纤维上并诱导羟基磷灰石晶体的成核。它们还可以通过吸附在晶体的特定面上来调节晶体形状。
Mammalian bones are composed of calcium phosphate crystals in a protein matrix. The major form of the calcium phosphate is hydroxyapatite. The most abundant matrix protein in bone is type I collagen. Collagen contributes to the mechanical properties of bone and is necessary for calcification of the tissue. In addition to collagen, several acidic proteins are present as minor components. Osteocalcin is a gamma-carboxyglutamic acid-containing protein of bone, which has an affinity to hydroxyapatite and can prevent crystal growth. Bone sialoprotein (BSP) and osteopontin are acidic glycophosphoproteins of bone. These proteins have RGD cell-attachment sequences and consecutive sequences of acidic amino acids. The poly glutamic acid sequences of BSP act as possible nucleation sites for hydroxyapatite crystals. Dentin phosphoprotein is the major non-collagenous protein of dentin. This protein has (Asp-Ser-Ser) repeat sequences, in which most of the Ser residues are phosphorylated. Some of these acidic matrix proteins are immobilized on the collagen fibrils and induce nucleation of hydroxyapatite crystals. They can also modulate crystal shape by adsorption on a specific face of the crystals.