Fig. 1.

Schematic representation of the gene encoding CREM/ICER. a The intron/exon structure of the CREM/ICER gene. Also shown are CREM promoters (P1, P3, and P4); ICER promoter (P2); glutamine-rich domains (Q1 and Q2); kinase-inducible domain (P-Box); and DNA-binding domains (DBD I and DBD II) of the ICER gene, containing leucine zipper and basic regions (bZIP). ATG, initiation methionine; TAA and TAG, stop codons. b Schematic mRNA structure of four ICER isoforms and corresponding exons. ICER I mRNA contains sequences encoding both DBD I and II, but the stop codon located in the carboxyl terminus of DBD I prevents insertion of DBD II into the protein