Chatterjee D, Neff L, Chakraborty M, Fabricant C, Baron R
Department of Orthopedics, Yale University School of Medicine, New Haven, Connecticut 06510.
Biochemistry. 1993 Mar 23;32(11):2808-12. doi: 10.1021/bi00062a011.
The osteoclast proton pump (OC H(+)-ATPase) differs from other vacuolar H(+)-ATPases (V-ATPases) in its sensitivity to vanadate and in the subunit composition of its catalytic domain, where isoforms of subunits A and B are expressed [Chatterjee et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 6257-6261]. In the present study, the sensitivity of the osteoclast H(+)-ATPase to various oxyanions was tested. The results indicate that H+ transport by microsomal preparations isolated from chicken osteoclasts is 20-100-fold more sensitive to nitrate that any other animal and fungal V-ATPases and 10-20-fold more sensitive than plant V-ATPases, as is the ATPase activity of the affinity-purified enzyme. This inhibition by nitrate is not due to a chaotropic effect of the oxyanion and is complete at 1 mM concentrations with an IC50 of 100 microM. In contrast, proton transport by the OC H(+)-ATPase was insensitive to other oxyanions (phosphate, sulfate, and acetate) which inhibit other V-ATPases. These results further demonstrate that the proton pump present in osteoclast membranes differs from other vacuolar ATPases. It is speculated that, since cells of the macrophage lineage can generate high intracellular concentrations of nitrate, it may be possible to physiologically or therapeutically regulate the activity of the OC H(+)-ATPase in the osteoclast without affecting the other V-ATPases in the same or in other cells.
破骨细胞质子泵（OC H(+)-ATP酶）在对钒酸盐的敏感性及其催化结构域的亚基组成方面与其他液泡H(+)-ATP酶（V-ATP酶）不同，其催化结构域中表达了亚基A和B的同工型[Chatterjee等人（1992年），《美国国家科学院院刊》89卷，6257 - 6261页]。在本研究中，测试了破骨细胞H(+)-ATP酶对各种含氧阴离子的敏感性。结果表明，从鸡破骨细胞分离的微粒体制剂的H+转运对硝酸盐的敏感性比任何其他动物和真菌的V-ATP酶高20 - 100倍，比植物V-ATP酶高10 - 20倍，亲和纯化酶的ATP酶活性也是如此。硝酸盐的这种抑制作用不是由于含氧阴离子的离液效应，在1 mM浓度下完全抑制，IC50为100 microM。相比之下，OC H(+)-ATP酶的质子转运对抑制其他V-ATP酶的其他含氧阴离子（磷酸盐、硫酸盐和乙酸盐）不敏感。这些结果进一步证明，破骨细胞膜中的质子泵与其他液泡ATP酶不同。据推测，由于巨噬细胞系的细胞可以在细胞内产生高浓度的硝酸盐，有可能在生理上或治疗上调节破骨细胞中OC H(+)-ATP酶的活性，而不影响同一细胞或其他细胞中的其他V-ATP酶。
