Abstract
In Brassica self-incompatibility, the self/non-self recognition between pollen and stigma is controlled by the multiple alleles at a single locus, S. The S locus contain three highly polymorphic genes, S-locus protein 11 (SP11), S-receptor kinase (SRK) and S-locus glycoprotein (SLG) genes. To date, we revealed that SP11 on the pollen coat acts as a ligand for its cognate SRK, and that SRK and an SLG-like 60 kDa protein (60K) together form a receptor complex for SP11 on the stigma membrane. However, the precise molecular structure of 60K is still unknown. Here we show that SRK/SLG expressed in yeast or COS-7 cells did not exhibit SP11 binding activity. We also show that 60K affinity-purified from stigmatic membrane exhibited slightly larger molecular size compared with stigmatic soluble form of SLG. We are now analyzing the molecular structure of 60K.
