The osteoclast proton pump differs in its pharmacology and catalytic subunits from other vacuolar H(+)-ATPases.
The osteoclast proton pump differs in its pharmacology and catalytic subunits from other vacuolar H(+)-ATPases.
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发表时间：
1992-11
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通讯作者：
Diptendu Chatterjee;M. Chakraborty;M. Leit;L. Neff;S. Jamsa-Kellokumpu;R. Fuchs;M. Bartkiewicz;Natividad Hernando;Roland Baron
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作者：
Diptendu Chatterjee;M. Chakraborty;M. Leit;L. Neff;S. Jamsa-Kellokumpu;R. Fuchs;M. Bartkiewicz;Natividad Hernando;Roland Baron
破骨细胞是源自造血骨髓中单核吞噬细胞系统的多核细胞。它们的功能是在骨骼生长和重塑过程中吸收骨骼。它们通过酸化封闭的细胞外空间（骨吸收室）来实现这一功能。高度纯化的鸡破骨细胞膜的内外囊泡对质子运输的分析揭示了一种新型的多亚基液泡样H(+)- atp酶的存在。与来自其他细胞类型或细胞器的H(+)- atp酶不同，破骨细胞囊泡中的质子转运和atp酶活性对两类抑制剂敏感，即v - atp酶抑制剂[n -乙基马来酰亚胺（NEM）和巴菲霉素A1]和钒酸盐（IC50 100 μ mol l-1），一种先前发现仅影响p - atp酶的抑制剂。Western blot分析显示，破骨细胞v - atp酶在形态上类似于液泡质子泵，含有几个液泡样亚基(115 × 10(3), 39 × 10(3)和16 × 10（3)M(r)）。然而，该酶的催化结构域的A和B亚基与其他v - atp酶不同。在破骨细胞中，亚基A的M(r)为63 × 10(3)，而不是67 × 10(3)-70 × 10(3)；相反，单核细胞、巨噬细胞和肾微粒体含有对钒酸盐不敏感的H(+)- atp酶，表达经典亚基a (70 x 10（3)M(r)）。此外，还发现了两种类型的57 × 10(3)-60 × 10(3)M(r) B亚基：它们被抗体识别，一种主要表达在破骨细胞中，另一种主要表达在骨髓细胞和肾微粒体中。初步克隆数据表明，在破骨细胞中表达的B亚基可能与脑亚型相似。因此，破骨细胞质子泵可能构成一类新的v - atp酶，具有独特的药理学和酶催化部分两个亚基的特异性同工型。
Osteoclasts are multinucleated cells derived from the mononuclear phagocyte system in the hematopoietic bone marrow. Their function is to resorb bone during skeletal growth and remodeling. They perform this function by acidifying an enclosed extracellular space, the bone resorbing compartment. Analysis of proton transport by inside-out vesicles derived from highly purified chicken osteoclast membranes has revealed the presence of a novel type of multisubunit vacuolar-like H(+)-ATPase. Unlike H(+)-ATPases derived from any other cell type or organelle, proton transport and ATPase activity in osteoclast vesicles are sensitive to two classes of inhibitors, namely V-ATPase inhibitors [N-ethyl-maleimide (NEM) and bafilomycin A1] and vanadate (IC50 100 mumol l-1), an inhibitor previously found to affect only P-ATPases. The osteoclast V-ATPase morphologically resembles vacuolar proton pumps and contains several vacuolar-like subunits (115 x 10(3), 39 x 10(3) and 16 x 10(3)M(r)), demonstrated by Western blot analysis. Subunits A and B of the catalytic domain of the enzyme, however, differ from that of other V-ATPases. In osteoclasts, subunit A has an M(r) of 63 x 10(3) instead of 67 x 10(3)-70 x 10(3); in contrast, monocytes, macrophages and kidney microsomes, which contain a vanadate-insensitive H(+)-ATPase, express the classical subunit A (70 x 10(3)M(r)). Moreover, two types of 57 x 10(3)-60 x 10(3)M(r) B subunits are also found: they are differentially recognized by antibodies and one is expressed predominantly in osteoclasts and the other in bone marrow cells and in kidney microsomes. Preliminary cloning data have indicated that the B subunit expressed in osteoclasts may be similar to the brain isoform. The osteoclast proton pump may, therefore, constitute a novel class of V-ATPase, with a unique pharmacology and specific isoforms of two subunits in the catalytic portion of the enzyme.