Sequence of short and long c-maf proteins generated by alternative RNA processing of transcripts from the c-maf gene. (A) A single letter code indicates the two sequences, with the long form identical to residues 1 through 372 of the short form. The basic region is underlined as a block, and individual residues that contribute to a presumptive leucine zipper are individually underlined. (B) This diagram summarizes the genome organization and codon sequences that account for the alternative RNA processing that generates the 2 forms of c-maf mRNA. The exon unique to the long form of the c-maf protein is located about 2.1 kb downstream of the polyadenylation signal used to generate the 4.4-kb mRNA that encodes the short form of the c-maf protein. The sequences of the exon-intron boundaries for the short mRNA are indicated, with the exon sequences in capital letters. The homology of the 4.4-kb mRNA to the avian c-maf genomic sequence indicates that the coding region and 3′ untranslated region are contained within a single exon.