This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Lang, W. C. Search for Related Content PubMed PubMed Citation Articles by Lang, W. C. Agricola Articles by Lang, W. C.

Articles

Glycoprotein Biosynthesis in Chlamydomonas¹

I. IN VITRO INCORPORATION OF GALACTOSE FROM UDP-[¹⁴C]GALACTOSE INTO MEMBRANE-BOUND PROTEIN

Fachbereich Biologie der Universität Kaiserslautern, 6750 Kaiserslautern, Federal Republic of Germany

A crude membrane fraction from Chlamydomonas reinhardii was found to catalyze D-galactose transfer from UDP-galactose to endogenous proteins. Highest incorporation rates were achieved by incubation at 25°C and pH 7.5 in the presence of 10 millimolar Fe²⁺. Hydrolytic studies on the labeled polymer revealed that radioactivity was attached to protein via an alkali-stable and acid-labile linkage. Identification of galactose as the only labeled sugar in the acid hydrolysate and results of a tentative estimation of the molecular weight of the charged alkaline degradation product indicate that monomeric galactose units are transferred to form an O-glycosidic bond with peptidyl hydroxyproline. No indications were found for a similar linkage to serine which, in contrast to the hydroxyproline-O-glycoside linkage, is acid-stable but is cleaved by -elimination. Chromatography of the sodium dodecyl sulfate-solubilized polymer on Sepharose-6B demonstrated that galactosyl residues are mainly associated with proteins which are of considerably higher molecular weight than are the majority of sodium dodecyl sulfate-denatured membrane proteins in this fraction.