Aggregation of sponge cells. A novel mechanism of controlled intercellular adhesion, basing on the interrelation between glycosyltransferases and glycosidases.
نویسندگان
چکیده
The biochemical and functional properties of p-glucuronidase and j?-galactosidase, isolated and partially purified from the sponge Geodia cydonium, were studied. The two glycosidases are not only localized in the cytoplasm but are also associated at a high activity with the cell membrane. The aggregation receptor, a low molecular weight cell surface-bound glycoprotein, is deglucuronylated by the action of the Geodia /3-glucuronidase both in the state at which the receptor is bound to the cell surface and in its isolated form. The deglucuronylated aggregation receptor can be reglucuronylated enzymatically by the extracellularly occurring homologous glucuronosyltransferase. Untreated cells lose their aggregation potency if they are incubated under conditions optimal for P-glucuronidase activity. Cells, depleted of membrane-bound pglucuronidase, do not show any reduction of their aggregation potency under identical conditions. Cells that carry on their cell surface deglucuronylated molecules and are biologically characterized by only a low aggregation potency can be reglucuronylated in the presence of glucuronosyltransferase and UDP-glucuronic acid. These restored cells show again the original high aggregation potency. From the results presented it is assumed that cell aggregation can occur after glucuronylation of the aggregation receptor by the glucuronosyltransferase via a linkage of the aggregation factor with the aggregation receptor. Some evidence is presented, indicating that cell separation is the consequence of an activation of the cell membrane bound P-glucuronidase, which results in a deglucuronylation of the aggregation receptor.
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عنوان ژورنال:
- The Journal of biological chemistry
دوره 254 4 شماره
صفحات -
تاریخ انتشار 1979