Difference in the genomic organizations of the related transcription factors Sp1 and Krox-20; possible evolutionary significance

Abstract

We report here part of the genomic sequence of the mouse homolog of the human gene encoding the transcription factor Spl. This gene belongs to a subfamily of zinc finger proteins, which includes another transcription factor, Krox-20. The analysis of the mouse Spl nucleotide sequence revealed that (i) the C-terminal part of the protein is conserved between man and mouse, consistent with a possible role in transcriptional activation; (ii) while the three Krox-20 zinc fingers are encoded by a unique exon, an intron separates the regions encoding fingers 2 and 3 of Spl. On the basis of this latter observation, we propose a model for the evolution of the Sp1/Krox-20 gene family which might shed some light on the role of introns in the evolution of modular proteins.

Key Words:

• DNA-binding domain
• Krox-20
• protein domain
• Sp1
• splicing
• zinc finger