Id gene expression during development and molecular cloning of the human Id-1 gene

Brain Res Mol Brain Res. 1995 Jun;30(2):312-26. doi: 10.1016/0169-328x(95)00017-m.


Id genes encode helix-loop-helix proteins that inhibit transcription by forming inactive heterodimers with basic helix-loop-helix (bHLH) proteins. bHLH proteins normally form either homodimers or heterodimers with other bHLH proteins and bind to a DNA sequence element activating transcription. Id-containing heterodimers are inactive because Id proteins lack the basic amino acid region necessary to form a DNA-binding domain. We have examined the relative levels of Id-1 and Id-2 mRNA during normal development and in malignant tissues. In the course of these experiments we cloned and sequenced the human Id-1 cDNA. Two related cDNA molecules encoding human Id-1 mRNAs were identified. Id-1a is a cDNA of 958 nucleotides and can encode a protein of 135 amino acids. Id-1b cDNA is 1145 nucleotides, can encode a protein of 149 amino acids, and appears to be a splice variant of Id-1a. The amino acid sequence of human Id-1 is greater than 90% homologous to that of mouse Id-1. The patterns of Id-1 and Id-2 expression during mouse development vary widely, and we detected Id-1 expression in human fetal and adult tissues from lung, liver, and brain. High Id-1 mRNA expression was found in many human tumor cell lines, including those isolated from nervous system tumors. We mapped Id-2 to human chromosome 2p25.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors
  • Cells, Cultured
  • Cloning, Molecular
  • DNA-Binding Proteins / genetics*
  • Gene Expression
  • Helix-Loop-Helix Motifs / genetics*
  • Humans
  • In Situ Hybridization
  • Inhibitor of Differentiation Protein 1
  • Mice
  • Molecular Sequence Data
  • Repressor Proteins*
  • Transcription Factors / genetics
  • Transcription, Genetic
  • Tumor Cells, Cultured


  • Basic Helix-Loop-Helix Transcription Factors
  • DNA-Binding Proteins
  • ID1 protein, human
  • Idb1 protein, mouse
  • Inhibitor of Differentiation Protein 1
  • Repressor Proteins
  • Transcription Factors

Associated data

  • GENBANK/S78825
  • GENBANK/S78986