FIG. 2.

GnRH stimulates inducible cAMP early repressor (ICER) in LβT2 cells. (A) Structure of the CREM gene that encodes ICER from an internal promoter (P2). Alternative splicing events give rise to four distinct ICER protein isoforms as depicted in the boxed field. DBD I and II, DNA-binding domain I and II; ATG, translational start site; TAA and TAG, translational stop codons; bZIP, basic leucine zipper motif. Regions encoding glutamine rich (Q1 and Q2) and kinase-inducible (P-Box) domains of the CREM gene, absent in ICER isoforms, are also depicted. The shICER sequence used in later experiments is common to all ICER isoforms. (B) ICER isoform mRNA levels in LβT2 cells at the indicated time points after stimulation with 100 nM GnRHAg. L19 mRNA levels are included as a control. (C) ICER isoform protein levels at the indicated time points after stimulation with 100 nM GnRHAg. β-Actin protein levels are shown as a loading control.