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1-Macroglobulin1
Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, MA 02139
We previously reported that synthesis of the serum glycoprotein
1-macroglobulin (
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
1-M purified from rats in the first week of deficiency;
1-M from more severely deficient rats showed significant depressions of mannose, galactose, and glucosamine.
KEY WORDS: vitamin A serum glycoprotein
1-macroglobulin glucosamine
1 This study was supported by National Institutes of Health grant AM 20476.
2 Current address is Eye Research Institute of Retina Foundation, Boston, MA 02114.
3 Current address is Department of Orthopedic Surgery, Tufts University School of Medicine, Boston, MA 02111.
4 To whom reprint requests should be sent.
Manuscript received 26 May 1981.