bHLH - Basic Helix Loop Helix Family Protein Emily Eder HC 70AL - Spring 2005
The Basic Helix Loop Helix • What characterizes the proteins in this family? • Are there any known functions? • In nonplant eukaryotes? • In plant eukaryotes, namely Arabidopsis? • What affect do mutant bHLH proteins have on plants, namely Arabidopsis?
Characterization of bHLH Family Proteins • Two distinct regions: • Basic Region • HLH Region • Basic Region • involved in DNA binding • HLH Region • functions as a dimerization domain
Known functions? • Plants? • Mammals?
Function of bHLH Family Proteins • Important regulatory components of transcription factors • Control a diversity of processes: • Cell proliferation • Cell lineage • Formation of homodimers and heterodimers
Effect of mutant bHLH Family Proteins in Nonplant Eukaryotes • Myogenesis • Heart Development • Pancreatic Development • Neurogenesis
Affect of mutations in bHLH family proteins in plant eukaryotes • Certain bHLH proteins affect photomorphogenic responses, including germination, blocking of greening, and expression of some light-regulated genes • Phytochromes (primary photoreceptors) affecting induction of germination to floral growth in higher plants
bHLH Family Proteins • Two regions - basic and HLH • Control a multitude of processes • Formation of homodimers and heterodimers • Mutants in non-plant eukaryotes have extensive affects • Mutant phenotypes in plant eukaryotes, namely Arabidopsis, are constantly being discovered