Tyrosine O-sulfate ester in proteoglycans |
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Authors: | U Rauch J Hollmann A Schmidt E Buddecke H Kresse |
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Institution: | Institut für Physiologische Chemie und Pathobiochemie, Universit?t Münster. |
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Abstract: | Tyrosine O-sulfate residues were detected in the protein core of sulfated proteoglycans. When cultured skin fibroblasts and arterial smooth muscle cells were incubated in the presence of 35S]sulfate, dermatan sulfate proteoglycan and chondroitin sulfate proteoglycan isolated from the culture medium contained tyrosine 35S]sulfate ester which accounted for 0.03%-0.82% of total 35S radioactivity incorporated into the sulfated proteoglycans. This corresponds to a tyrosine sulfation of every second (fibroblasts) and every 10th (smooth muscle cells) dermatan sulfate proteoglycan molecule. 3H]Tyrosine labeling of fibroblast dermatan sulfate proteoglycan gave a similar stoichiometry. However, the relative proportion of tyrosine 35S]sulfate in proteoglycans from arterial tissue was about 10 times higher than in that from cultured arterial cells. Pulse chase experiments with 35S]sulfate revealed that tyrosine sulfation is a late event in the biosynthesis of dermatan sulfate proteoglycan from fibroblasts and occurs immediately prior to secretion. Cultured skin fibroblasts from a patient with a progeroid variant (Kresse et al. 1987, Am. J. Hum. Gen. 41, 436-453) which exhibit a partial deficiency to synthesize dermatan sulfate proteoglycan were shown to form and to secrete a tyrosine-sulfated but glycosaminoglycan-free protein core, thus confirming a selective and independent 35S]sulfate labeling of the protein core. |
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