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Multiple G‐protein involvement in parathyroid hormone regulation of acid production by osteoclasts
Author(s) -
May Lisa G.,
Gay Carol V.
Publication year - 1997
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(199701)64:1<161::aid-jcb18>3.0.co;2-o
Subject(s) - parathyroid hormone , parathyroid hormone related protein , chemistry , hormone , medicine , endocrinology , microbiology and biotechnology , biochemistry , biology , calcium
The involvement of multiple G‐proteins in parathyroid hormone regulation of acid production was demonstrated in a highly enriched osteoclast population. Osteoclasts were isolated from the endosteum of 2.5 to 3‐week‐old chicken tibia using sequential enzymatic digestion. Single cell analysis of acid production was accomplished using microscope photometry and vital staining with acridine orange, a hydrogen ion concentration sensitive fluorescent dye. Lithium chloride, an uncoupler of G‐proteins from their respective receptors, blocked parathyroid hormone stimulated production of acid. Cholera toxin, which permanently activates G s ‐proteins, mimicked PTH stimulation. Pertussis toxin, which prevents receptor interaction with G i ‐ and G o ‐proteins, blocked both 10 8 M and 10 11 M PTH stimulated acid production, suggesting that the pertussis toxin‐sensitive G‐protein is utilized at both PTH concentrations. Immunoblots of osteoclast plasma membrane proteins, using a panel of antibodies generated against specific G‐protein α subunits, revealed a 48 kDa G s α, a 41 G o α, a 34 kDa G i α‐3, and a unique 68 kDa Gα subunit, with the 41 kDa and 34 kDa bands being the most intense. Immunoblots of osteoblast plasma membrane proteins had a substantially different profile with the most intense bands being a G s α (48 kDa) and a G o α (36 and 38 kDa). The studies suggest the utilization of at least two different G‐proteins in the parathyroid hormone regulation of acid formation by osteoclasts, a G s and a pertussis toxin‐sensitive G‐protein (G o and/or G i α‐3). J. Cell. Biochem. 64:161–170. © 1997 Wiley‐Liss, Inc.