The adenovirus E1A protein both activates and represses gene expression to promote cellular proliferation and inhibit differentiation. CREG (cellular repressor of E1A-stimulated genes) is a cellular protein that antagonizes transcriptional activation and cellular transformation by E1A. CREG was initially isolated in a yeast two-hybrid screen due to its interaction with the TATA-binding protein, TBP. A member of the CREG family, CREG2 (cellular repressor of E1A-stimulated genes 2) is a novel protein that shares 35% homology with CREG and is expressed at highest levels in brain. CREG2 is a secreted protein containing 290 amino acids whose N-terminus is thought to function as a signal sequence. The gene encoding CREG2 maps to human chromosome 2, which consists of 237 million bases, encodes over 1,400 genes and makes up approximately 8% of the human genome. A number of genetic diseases are linked to genes on chromosome 2 including Harlequin icthyosis, sitosterolemia and Alstr syndrome.
