The Crb1 are transmembrane proteins required for determination of retinal cell polarity. On the other hand, the peptide motif called EGF-like repeat is involved in various protein interactions required for tissue development. Using a probe for the EGF-like repeat motifs, we isolated a novel splice variant of Crb1 from a cDNA library prepared from day-14 mouse embryos and termed it Crb1s.