Plasma membrane osteoclasts

Bekker PJ, Gay CV. 1990. Characterization of a Ca2+-ATPase in osteoclast plasma membrane. J Bone Miner Res 5 557-67. 

Moonga BS, Li S, Iqbal J, Davidson R, Shankar VS, Bevis PJ, Inzerillo A, Abe E, Huang CL, Zaidi M. 2002. Ca2+ influx through the osteoclastic plasma membrane ryanodine receptor. Am J Physiol Renal Physiol 282 F921-32. 

Zaidi M, Shankar VS, Tunwell R, Adebanjo OA, Mackrill. 1. Pazianas M, O Connell D, Simon BJ, Rifkin BR, Venkitaraman AR, Huang, CL-H, Lai FA. 1995. A ryanodine receptor-like molecule expressed in the osteoclast plasma membrane functions in extracellular Ca2+ sensing. J Clin Invest 96 1582-90. 

Oursler, M.J., Collin-Osdoby, P., Li, L., Schmitt, E., and Osdoby, P. 1991. Evidence for an immunological and functional relationship between superoxide dismutase and a high molecular weight osteoclast plasma membrane glycoprotein. J. Cell. Biochem. 46, 331-344. 

C1C-6 is a late endosomal chloride transporter. Its disruption in mice led to lysosomal storage disease. C1C-7 is expressed in late endosomes and lysosomes. It needs Ostml as (3-subunit [3]. The disruption of either C1C-7 or Ostml in mice and man leads to severe osteopetrosis, retinal degeneration, and a severe lysosomal storage disease. ClC-7/Ostml is highly expressed in osteoclasts. In these cells, it is inserted together with the proton pump into the specialized plasma membrane ( ruffled border ) that faces the reabsorption lacuna. Osteoclasts are still present in C1C-7 knockout... 

Part of the metabolic machinery of an osteoclast resembles the red cell and the renal tubule cells because all of these cell types contain the enzyme carbonic anhydrase (carbonate dehydratase) which generates acid, that is protons, and have ion pumps in their plasma membranes. The mechanism of bone resorption requires the action of cathepsin and metalloproteinase-9 working in an acidic environment (Figure 9.8). 

Nakamura, H. (1995) Localization of CD44, the hyaluronate receptor, on the plasma membrane of osteocytes and osteoclasts in rat tibiae. Cell Tissue Research 280 225-233... 

Plasma membrane of osteoclasts and some kidney tubule cells... 

Activity The C. exhibit antifungal, antiviral, immunosuppressive, and cytotoxic activities. The C. became excellent aids in biochemistry after it was recognized that they are specific inhibitors of ATPases of the V-type (C. A Kj=0.02 nM) and in this respect are even superior to the related bafilomycin A,. Since V-type ATPases are active in the plasma membranes of osteoclasts inhibition of these enzymes has been discussed as a possibility for treatment of osteoporosis. ATPases of the P-type are inhibited in the micromolar range while no effect has been observed on F-type ATPases. Semi-synthetic, more stable 21-deoxyconca-namycins are promising candidates for further development. 

Sakai, H., Moriura, Y., Notomi, T., Kawawaki, J., Ohnishi, K., Kuno, M., 2010. Phospholipase C-dependent Ca -sensing pathways leading to endocytosis and inhibition of the plasma membrane vacuolar H -ATPase in osteoclasts. American Journal of Physiology. Cell Physiology 299, C570-C578. 

CalcitrioPs action primary function is in regulating plasma calcium concentration. In health, the plasma total calcium concentration is tightly controlled at 2.35-2.55 mmol/1. Only the ionized or free fraction, amounting to about 50% of the total, is physiologically active in for example, maintenance of membrane electrical potential and bone formation. The hormone causes increased bone resorption via activation of osteoclasts (see Section 9.4) and increased intestinal absorption of calcium following the synthesis of a specific binding protein in mucosal cells. As described in Section 4.7, some... 

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