Letter | Published:

Localisation of plasma α2HS glycoprotein in mineralising human bone

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Abstract

THE protein of the organic matrix of bone consists mainly of collagen in association with a small proportion of non-collagenous proteins. When bone is decalcified, much of the non-collagenous protein can be solubilised in conditions of neutral pH but the collagen remains insoluble. Extracts of decalcified bone prepared in this manner contain small amounts of plasma proteins which derive in part from the presence of blood vessels within the tissue1,2. There is evidence, however, that some plasma proteins, including albumin, form an integral part of the calcified matrix3. When 14C-glucosamine or 14C-glucosamine-labelled rabbit total plasma protein is injected into a rabbit, some activity is incorporated into the bone4. Using the procedure of Herring5 to separate the EDTA-soluble proteins of the bone matrix, most of the activity was shown to be present in the less acidic glycoprotein fraction, much of this in one glycoprotein which was also present as a minor component of blood4. This G2B glycoprotein had the electrophoretic mobility of an α globulin and a molecular weight by SDS gel electrophoresis6 of about 50,000. Studies by Ashton et al. (private communication) support the view that the G2B glycoprotein they have investigated in rabbit4 and bovine bone6 is the analogue of human α2HS glycoprotein.

References

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    Burchard, J., Havez, R., and Dautrevaux, M., Bull. Soc. chim. Biol., 48, 851–861 (1966).

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    Ashton, B. A., Herring, G. M., Owen, M. E., and Triffitt, J. T., Israel J. med. Sci., 7, 409–411 (1971).

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    Ashton, B. A., Triffitt, J. T., and Herring, G. M., Eur. J. Biochem., 45, 525–533 (1974).

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    Poole, A. R., in Methological Developments in Biochemistry, 4 (edit. by Reid, E.), 1 (Longmans, London, 1974).

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    Schmid, K., and Bürgi, W., Biochim. biophys. Acta, 47, 440–453 (1961).

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