Fig. 4. zpg encodes a Drosophila gap junction protein – Innexin-4. (A) zpg genomic region in 65B5-65C1 (top) with position of P element insert in zpg³. Predicted transcripts (horizontal arrows); 6.15 kb genomic fragment that rescued zpg (bold bottom line). (B) Predicted topology of the Zpg protein, showing four transmembrane domains and conserved extracellular cysteine residues. Asterisks indicate sites of mutations in EMS-induced zpg alleles. (C) Multiple alignment and comparison (ClustalW) of eight innexin family members in Drosophila. Predicted transmembrane domains (unbroken bars); conserved predicted extracellular cysteine residues (asterisks); the oligopeptide used to generate the anti-sera is based on residues 345-367 (broken line). Amino acid changes in zpg alleles indicated above the protein sequence. ($) Stop codon; (#) base pair change at the splice acceptor site in zpg^z-2679 allele leads to an altered predicted amino acid sequence starting at amino acid residue D(93).