In Brassicaceae, self-incompatible plants have a self/non-self recognition system. This is sporophytically controlled by multiple alleles at a single locus (S). S-locus glycoproteins, as well as S-receptor kinases, are in linkage with the S-alleles [1]. This region is inferred to be a domain due to it having other domains adjacent to it.

1: Evolutionary aspects of the S-related genes of the Brassica self-incompatibility system: synonymous and nonsynonymous base substitutions. Hinata K, Watanabe M, Yamakawa S, Satta Y, Isogai A; Genetics 1995;140:1099-1104. PMID:7672580

2: Polymorphism of the S-locus glycoprotein gene (SLG) and the S-locus related gene (SLR1) in Raphanus sativus L. and self-incompatible ornamental plants in the Brassicaceae. Sakamoto K, Kusaba M, Nishio T; Mol Gen Genet 1998;258:397-403. PMID:9648745