Fig. 1.

Disruption of the normal PSI–U1 snRNP interaction causes defects in Drosophila male courtship behavior. (A) Diagram of the PSI protein, which is composed of four RNA-binding KH domains and the AB repeat domain that interacts with U1 snRNP. (B) Immunoblot of fly head extracts from PSI-null mutant flies that carry transgenes expressing PSIΔAB or full-length PSI proteins, with wild-type Canton S fly head extracts serving as positive control. Protein detected with specific antibody probes are indicated at the right. (C, Left) Behavioral space densities for the male PSIΔAB and full-length PSI fly strains in the presence of a Canton S young virgin female. Colored lines indicate regions of the space corresponding to behaviors associated with the male courtship ritual. (Right) Probability that a male fly of the PSIΔAB strain (open bars) or the full-length PSI strain (solid bars) performs each of several courtship behaviors in the presence of a young Canton S virgin female fly. Mean of seven individual flies of each strain, with ±SE shown. See also Movies S1–S3.