The human elk-1 gene family: the functional gene and two processed pseudogenes embedded in the IgH locus.

Elk-1 is a transcription factor whose activation by several mitogen-activated protein kinases (MAPKs) mediates the immediate early responses of the c-fos promoter to growth factors and other stimuli. Here, we report the structure of the human elk-1 gene, which we have localized about 6.5kb upstream of the properdin gene on the X chromosome. The coding sequence is interrupted by four introns; two additional introns lie within the 5' untranslated region. We have also found two elk-1-related processed pseudogenes in the human immunoglobulin heavy chain (IgH) locus, accounting for 'elk-2' previously visualized by in-situ hybridization at 14q32. A processed pseudogene evidently inserted downstream of a primordial immunoglobulin Calpha gene and was duplicated along with part of the IgH locus. Gene/pseudogene sequence comparisons and Southern blots of primate DNAs suggest that both the pseudogene insertion and the locus duplication occurred between about 30 and 60 million years ago.