title: A tissue-specific transcription factor containing a homeodomain specifies a pituitary phenotype.
abstract: Multiple related cis-active elements required for cell-specific activation of the rat prolactin gene appear to bind a pituitary-specific positive transcription factor(s), referred to as Pit-1. DNA complementary to Pit-1 mRNA, cloned on the basis of specific binding to AT-rich cell-specific elements in the rat prolactin and growth hormone genes, encodes a 33 kd protein with significant similarity at its carboxyl terminus to the homeodomains encoded by Drosophila developmental genes. Pit-1 mRNA is expressed exclusively in the anterior pituitary gland in both somatotroph and lactotroph cell types, which produce growth hormone and prolactin, respectively. Pit-1 expression in heterologous cells (HeLa) selectively activates prolactin and growth hormone fusion gene expression, suggesting that Pit-1 is sufficient to confer a characteristic pituitary phenotype. The structure of Pit-1 and its recognition elements suggests that metazoan tissue phenotype is controlled by a family of transcription factors that bind to related cis-active elements and contain several highly conserved domains.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000032:analysis / Q000235:genetics; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics; D006367:HeLa Cells; D007150:Immunohistochemistry; D008297:Male; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D009928:Organ Specificity; D010641:Phenotype; D010903:Pituitary Gland, Anterior / Q000032:analysis*; D011388:Prolactin / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D012333:RNA, Messenger; D014157:Transcription Factors; D011388:Prolactin; D013006:Growth Hormone; D004247:DNA