S-Locus-Specific Glycoproteins Associated with Self-Incompatibility in Brassica campestris

Specific S-glycoproteins were isolated from three Brassica campestriscultivars homozygous with respect to the S-alleles S₈, S₉ andS₁₂. Amino acid sequences of various peptide fragments of theS-proteins were determined using a gas-phase protein sequencer,and a nearly complete amino acid sequence of the S₈-glycoproteinwas determined on the basis of the revised cDNA sequence ofthe B. oleracea S-specific glycoprotein. The lysyl endopeptidasefragments of S₉ and S₁₂-glycoproteins were aligned in comparisonwith the sequence of the S₈-glycoprotein. Although extensivesequence homology was evident among the three S-glycoproteins,the sequences of the middle part were relatively different fromeach other. The numbers and positions of N-glycosylation alsodiffered among the S-glycoproteins of Brassica species. (Received April 20, 1987; Accepted July 29, 1987)