Download bHLH - Basic Helix Loop Helix Family Protein

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
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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