The chicken delta 1-crystallin gene promoter: binding of transcription factor(s) to the upstream G+C-rich region is necessary for promoter function in vitro.

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Abstract
There are two linked .delta.-crystallin genes in the chicken (5'' .delta.1-.delta.2 3''). Only the .delta.1 gene has been shown definitively to be active in the lens. Transcription of deletion mutants, reported here, shows that the sequences necessary for the functioning of the .delta.1 promoter in a HeLa cell extract are located upstream from the RNA initiation site, between nucleotide positions -121 and -38. This region includes a number of G + C-rich motifs, including one hexanucleotide sequence, CCGCCC, that is repeated six times in the simian virus 40 (SV40) promoter. Competition experiments with purified fragments from the .delta.1-crystallin gene promoter showed that binding of transcription factor(s) from the HeLa extract to this G + C-rich region is required for promoter activity in vitro. Further, competition experiments using three different fragments from the SV40 promoter suggest that the transcription by binding to the G + C-rich 21-base-pair repeats of the SV40 promoter, and differs from that which interacts with the SV40 enhancer region.