Vol.53,No.4, 1973 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS MANNOSE TRANSFER FROM MANNOLIPID TO ENDOGENOUS ACCEPTORS IN HAMSTER LIVER Nancy Maestri and Luigi De Luca Differentiation Control Section Lung Cancer Branch National Cancer Institute National Institutes of Health Bethesda, Maryland 20014 Received July 11,1973 SUMMARY 14 Hamster liver C-mannolipid, prepared by DEAE-cellulose chromatography of the organic extract, is shown to be a more efficient donor of mannose to endogenous glycoproteins then guanosine-diphosphate-mannose. Analysis of endogenous acceptors after proteolysis reveals that several compounds separated by DEAE;zephadex chromatography are labeled by both I‘%- mannolipid and GDP-mannose C. Although the biosynthesis of polyprenyl-phosphate-mannose compounds has been reported for several tissues (1 + lo), no firm demonstration has as yet appeared of their possible role as donors of mannose to endogenous acceptor glycoproteins. We report here that a cell-free system from hamster liver can use mannolipid about 5 fold more effectively than GDP-mannose in a transfer reaction to endogenous glycopeptides. The resulting glycopeptides are separated by DEAE-sephadex chromato- graphy and shown to contain covalently bound 14C-mannose. Methods and Results 14 14 To study the transfer of C-mannose from C-mannolipid to endogenous acceptors, the labeled mannolipid was synthesized essentially as previously described (5). Details are given under Fig, 1A legend. The bulk DEAE-cellulose fraction was used as the mannose donor. Fig. 1 illustrates the kinetics of the trans- 1344 Copyright 0 1973 by Academic Press, Inc. All rights of reproduction in any form reserved.