Fig. 4. C. elegans NPH-1 and NPH-4 protein domain structures. (A) The C. elegans NPH-1 protein consists of two coiled-coil domains, an E-rich domain, a QP-rich domain (glutamate-proline rich domain), cytochrome P450E, an SH3 domain, and the nephrocystin homology domain (NHD). The deleted region (amino acids 281-641) in the nph-1(ok500) mutant is indicated as well as the nephrocystin-4 mammalian interaction region (C-terminal 131 amino acids). The protein sequence is based on the mRNA sequence derived from NM_063897. (B) The NPH-4 protein in C. elegans does not exhibit any well-characterized domains. The deletion, which spans amino acids 86-264 in nph-4(tm925) mutants, and the region involved in the interaction with mammalian nephrocystin-1 (N-terminal 176 amino acids) are indicated. The protein sequence is based on the mRNA sequence from AY959881.