Effect of vitamin A deficiency on glycosylation of rat serum alpha 1-macroglobulin.

We previously reported that synthesis of the serum glycoprotein alpha 1-macroglobulin (alpha 1-M) was decreased in vitamin A-deficient rats. In a reexamination of this conclusion we have shown that the primary synthetic change, reflected by labeled glucosamine uptake, was an underglycosylation which initially has no effect on the glycoprotein's concentration in serum. The severity of this lesion developed progressively and was independent of the glycosylation of total serum glycoprotein, at least up to 11 days after onset of the deficiency. Less glucosamine was demonstrated chemically in a alpha 1-M purified from rats in the first week of deficiency; alpha 1-M from more severely deficient rats showed significant depressions of mannose, galactose, and glucosamine.