Functional and structural characterization of the human gene BHLHB5, encoding a basic helix-loop-helix transcription factor

Genomics. 2002 Sep;80(3):311-8. doi: 10.1006/geno.2002.6833.


The genes encoding basic helix-loop-helix (bHLH) transcription factors have been implicated in many aspects of neural development, including cell growth, differentiation, and cell migration. Using both genomic and cDNA mouse and human clones encoding a neural-specific bHLH protein, human BHLHB5 was cloned and mapped to a region on chromosome 8q13 that segregates with Duane syndrome. Genomic sequence analysis of human BHLHB5 and mouse Bhlhb5 revealed that they contain a single exon encoding 381- and 355-amino-acid bHLH proteins, respectively. Multiple amino acid sequence alignments of the Bhlhb5 family members revealed several conserved motifs and an identical 147-amino-acid carboxy-terminal region that contains a 60-amino-acid bHLH domain. A 27-bp trinucleotide repeat (CAG)(9) encoding polyserine was found in human BHLHB5, but only one CAG was found at the corresponding position in the mouse Bhlhb5 and hamster BETA3 genes. Northern blot analysis of human BHLHB5 revealed brain-specific expression with the highest abundance in the cerebellum. Mouse Bhlhb5 can strongly repress a human PAX6 promoter.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors
  • Brain / metabolism
  • Cricetinae
  • DNA-Binding Proteins / genetics
  • Eye Proteins
  • Helix-Loop-Helix Motifs*
  • Homeodomain Proteins / genetics
  • Humans
  • Mice
  • Molecular Sequence Data
  • Organ Specificity
  • PAX6 Transcription Factor
  • Paired Box Transcription Factors
  • Promoter Regions, Genetic
  • Repressor Proteins
  • Sequence Alignment
  • Transcription Factors / genetics*


  • BETA3 protein, Cricetinae
  • BHLHE22 protein, human
  • Basic Helix-Loop-Helix Transcription Factors
  • DNA-Binding Proteins
  • Eye Proteins
  • Homeodomain Proteins
  • PAX6 Transcription Factor
  • PAX6 protein, human
  • Paired Box Transcription Factors
  • Pax6 protein, mouse
  • Repressor Proteins
  • Transcription Factors

Associated data

  • GENBANK/AF504925
  • OMIM/126800
  • RefSeq/NM_021560