MODULATION OF CRYSTAL-FORMATION BY BONE PHOSPHOPROTEINS - ROLE OF GLUTAMIC ACID-RICH SEQUENCES IN THE NUCLEATION OF HYDROXYAPATITE BY BONE SIALOPROTEIN
MODULATION OF CRYSTAL-FORMATION BY BONE PHOSPHOPROTEINS - ROLE OF GLUTAMIC ACID-RICH SEQUENCES IN THE NUCLEATION OF HYDROXYAPATITE BY BONE SIALOPROTEIN
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DOI：
10.1042/bj3020175
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发表时间：
1994-08-15
影响因子：
4.1
通讯作者：
GOLDBERG, HA
中科院分区：
文献类型：
--
作者：
HUNTER, GK;GOLDBERG, HA
骨唾液蛋白（BSP）是一种骨特异性糖蛋白，含有磷酸丝氨酸磺基酪氨酸残基和连续的谷氨酸残基区域。本实验室最近的研究表明，BSP能够在稳态琼脂糖凝胶系统中使骨矿物羟基磷灰石成核。我们在这里表明，羧酸基团的化学修饰废除BSP的成核活性，但酶促脱磷酸化没有影响。聚（L-谷氨酸）和聚（D-谷氨酸）也能诱导羟基磷灰石的形成，但聚（L-天冬氨酸）或聚（L-赖氨酸）不能诱导羟基磷灰石的形成。钙网蛋白是一种具有连续谷氨酸残基的短序列的肌肉蛋白，也缺乏成核活性。这些结果表明，BSP的羟基磷灰石的成核涉及一个或两个富含谷氨酸的序列。基于这些发现和其他人，我们建议，聚羧酸序列代表了一个一般网站的生长调节蛋白质和生物晶体之间的相互作用。
Bone sialoprotein (BSP) is a bone-specific glycoprotein containing phosphoserine sulphotyrosine residues and regions of contiguous glutamic acid residues. Recent studies in this laboratory have shown that BSP is capable of nucleating the bone mineral hydroxyapatite in a steady-state agarose gel system. We show here that chemical modification of carboxylate groups abolishes the nucleation activity of BSP, but enzymic dephosphorylation has no effect. Formation of hydroxyapatite is also induced by poly(L-glutamic acid) and poly(D-glutamic acid), but not by poly(L-aspartic acid) or poly(L-lysine). Calreticulin, a muscle protein with short sequences of contiguous glutamic acid residues, also lacks nucleation activity. These findings suggest that the nucleation of hydroxyapatite by BSP involves one or both of the glutamic acid-rich sequences. Based on these findings and others, we propose that polycarboxylate sequences represent a general site for growth-modulating interactions between proteins and biological crystals.