Id gene expression during development and molecular cloning of the human Id-1 gene.
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.
Zhu
W
W
Preuss Laboratory, Department of Neurological Surgery, San Francisco, CA 94143, USA.
Dahmen
J
J
Bulfone
A
A
Rigolet
M
M
Hernandez
M C
MC
Kuo
W L
WL
Puelles
L
L
Rubenstein
J L
JL
Israel
M A
MA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics*; D015870:Gene Expression; D018257:Helix-Loop-Helix Motifs / Q000235:genetics*; D006801:Humans; D017403:In Situ Hybridization; D051798:Inhibitor of Differentiation Protein 1; D051379:Mice; D008969:Molecular Sequence Data; D012097:Repressor Proteins; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D051798:Inhibitor of Differentiation Protein 1; D012097:Repressor Proteins; D014157:Transcription Factors; C497453:ID1 protein, human; C497455:Idb1 protein, mouse