This family consists of a number of cysteine rich SLR1 binding pollen coat like proteins. Adhesion of pollen grains to the stigmatic surface is a critical step during sexual reproduction in plants. In Brassica, S locus-related glycoprotein 1 (SLR1), a stigma-specific protein belonging to the S gene family of proteins, has been shown to be involved in this step. SLR1-BP specifically binds SLR1 with high affinity. The SLR1-BP gene is specifically expressed in pollen at late stages of development and is a member of the class A pollen coat protein (PCP) family, which includes PCP-A1, an SLG (S locus glycoprotein)-binding protein [1].

1: Isolation and characterization of pollen coat proteins of Brassica campestris that interact with S locus-related glycoprotein 1 involved in pollen-stigma adhesion. Takayama S, Shiba H, Iwano M, Asano K, Hara M, Che FS, Watanabe M, Hinata K, Isogai A; Proc Natl Acad Sci U S A 2000;97:3765-3770. PMID:10716697