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INTEGRAL MEMBRANE PROTEIN 2A; ITM2A

INTEGRAL MEMBRANE PROTEIN 2A; ITM2A

Alternative titles; symbolsE25AHGNC Approved Gene Symbol: ITM2ACytogenetic location: Xq21.1 Genomic coordinates (GRCh38): X:79,360,383-79,367,333 (from NCBI)...

Alternative titles; symbols

  • E25A

HGNC Approved Gene Symbol: ITM2A

Cytogenetic location: Xq21.1 Genomic coordinates (GRCh38): X:79,360,383-79,367,333 (from NCBI)

▼ Cloning and Expression
By differential screening of a cDNA library constructed from in vitro cultured condyles, Deleersnijder et al. (1996) isolated a novel gene in the mouse, which they called E25A, or integral membrane protein-2 (Itm2). The full-length E25A cDNA was predicted to encode a type II integral membrane protein of 263 amino acid residues. In situ hybridization showed that E25A is expressed in the outer perichondrial rim of the postnatal mandibular condyle, which contains the proliferating progenitor cells, but not in the deeper layers of the condyle containing the more differentiated chondroblasts and chondrocytes. Strong in situ hybridization signals were also detected on bone trabeculae of mature bone, in tooth germs, and in hair follicles. Northern blot analysis showed strong expression in osteogenic tissues, such as neonatal mouse calvaria, paws, and tail, and in skin. Homology searches of DNA databanks showed that E25A belongs to a novel multigene family, containing at least 3 members in both man and mouse.

Mao et al. (1998) found that the human homolog of murine E25A is expressed in human CD34+ hematopoietic stem/progenitor cells.

By subtractive hybridization for sequences differentially expressed by plasmacytoid dendritic cells, Rissoan et al. (2002) detected ITM2A, which they designated BRI3. The deduced type II transmembrane protein contains an N-terminal cytosolic domain, an uncleaved signal anchor sequence, and a tyrosine-rich C-terminal extracellular domain. The 312-amino acid mouse Itm2a protein shares 91% homology with human ITM2A. RT-PCR of human lymphoid cells showed higher expression of ITM2A in plasmacytoid dendritic cells than in monocytes and monocyte-derived dendritic cells. A faint band was detected in CD34-derived dendritic cells. Northern blot analysis revealed a 2.1-kb transcript in several lymphoid tissues, including appendix, peripheral blood leukocytes, bone marrow, fetal liver, with lower levels in spleen, lymph nodes, and thymus.

▼ Mapping
Deleersnijder et al. (1996) mapped the mouse E25A gene to the X chromosome.

By fluorescence in situ hybridization, Pittois et al. (1999) mapped the mouse Itm2a gene to chromosome XA2-A3 and the human homolog to Xq13.3-q21.2.

Tags: Xq21.1