The sexual agglutinins in Chlamydomonas eugametos are sulphated glycoproteins

Sexual adhesion in the green alga Chlamydomonas eugametos is mediated by hydroxyproline-containing glycoproteins (agglutinins). The agglutinins were metabolically labelled with [35S]sulphate. The sulphur-containing amino acids methionine and cysteine were not detectably labelled; little or no sulphated tyrosine was detected. This indicated that the radioactive label had been largely or exclusively incorporated into sulphated sugar residues. Acid hydrolysis released essentially all radioactivity as free sulphate. Short periods of hydrolysis released sulphated oligosaccharides. /%Elimination released about 20-25 % of the sulphated saccharides, indicating that these are 0-linked to serine or threonine or both. The remaining sulphated sugar chains are presumably 0-linked to hydroxyproline. It is proposed that the sulphated sugars of the agglutinins play a role in sexual adhesion