Alternative titles; symbols
HGNC Approved Gene Symbol: KRT32
Cytogenetic location: 17q21.2 Genomic coordinates (GRCh38): 17:41,459,513-41,467,386 (from NCBI)
See KRTHA1 (601077) for general information on hair keratins.
By screening a human scalp cDNA library with a mouse Ha2 cDNA, Rogers et al. (1995) cloned a cDNA encoding KRTHA2, or HA2. The predicted protein has 405 amino acids, including a 41-amino acid C terminus. The amino acid sequences of the human and mouse HA2 proteins are 81% identical. Northern blot analysis detected HA2 transcripts in human scalp but not unhaired breast epidermis.
Rogers et al. (1998) reported that the deduced KRTHA2 protein has 448 amino acids. By RT-PCR, Rogers et al. (1998) showed that KRTHA2 is expressed in the human hair follicle. See Langbein et al. (1999) for further details on the expression pattern of the KRTHA2 gene in the hair follicle.
Winter et al. (1994) found that expression of mouse Ha2 mRNA occurs early in hair morphogenesis and is strictly limited to the cuticle of the hair shaft.
Rogers et al. (1996) isolated the HA2 genomic sequence. The HA2 gene and its flanking sequences span over 14 kb. The gene contains 7 exons; the 6 conserved introns are located in the region encoding the alpha-helical domain. The 5-prime flanking sequence contains a LEF1 (153245)-binding site, which is present in several hair follicle-associated genes. Zhou et al. (1995) showed that LEF1 is important for hair patterning and morphogenesis.
By fluorescence in situ hybridization, Rogers et al. (1995) mapped the HA2 gene to 17q12-q21. Rogers et al. (1996) found that the HA5 (KRTHA5; 602764) gene is located 8 kb upstream of the HA2 gene. Rogers et al. (1998) isolated and characterized 2 overlapping human PAC clones that cover 190 kb on 17q12-q21 and contain 9 type I hair keratin genes, 1 transcribed hair keratin pseudogene, and 1 orphan exon. The order of the genes is 5-prime--KRTHA6 (604540)--KRTHA5--KRTHA2--orphan exon--KRTHA8 (604542)--KRTHA7 (604541)--pseudogene--KRTHA1--KRTHA4 (602763)--KRTHA3B (602762)--KRTHA3A (602761)--3-prime. The hair keratin genes range in size from 4.2 to 7.5 kb, and the genes are separated from each other by 5.5 to 18.4 kb; all are located within about 140 kb. Each gene is transcribed from the 5-prime to 3-prime direction. Based on sequence homologies, the genes can be grouped into 3 subclusters of tandemly arranged genes. One subcluster, group A, consists of KRTHA1, KRTHA3A, KRTHA3B, and KRTHA4, which share 89% overall amino acid identity. A second subcluster, group B, contains KRTHA7 and KRTHA8, as well as the hair keratin pseudogene, which the authors called HAA. The functional hair keratins and hypothetical HAA hair keratin share approximately 81% overall amino acid identity. The third subcluster, group C, consists of the structurally less related hair keratins KRTHA2, KRTHA5, and KRTHA6, which share about 70% amino acid identity.
Langbein, L., Rogers, M. A., Winter, H., Silke, P., Beckhaus, U., Rackwitz, H.-R., Schweizer, J. The catalog of human hair keratins. I. Expression of the nine type I members in the hair follicle. J. Biol. Chem. 274: 19874-19884, 1999. [PubMed: 10391933] [Full Text: https://doi.org/10.1074/jbc.274.28.19874]
Rogers, M. A., Nischt, R., Korge, B., Krieg, T., Fink, T. M., Lichter, P., Winter, H., Schweizer, J. Sequence data and chromosomal localization of human type I and type II hair keratin genes. Exp. Cell Res. 220: 357-362, 1995. [PubMed: 7556444] [Full Text: https://doi.org/10.1006/excr.1995.1326]
Rogers, M. A., Winter, H., Langbein, L., Krieg, T., Schweizer, J. Genomic characterization of the human type I cuticular hair keratin hHa2 and identification of an adjacent novel type I hair keratin gene hHa5. J. Invest. Derm. 107: 633-638, 1996. [PubMed: 8823373] [Full Text: https://doi.org/10.1111/1523-1747.ep12584243]
Rogers, M. A., Winter, H., Wolf, C., Heck, M., Schweizer, J. Characterization of a 190-kilobase pair domain of human type I hair keratin genes. J. Biol. Chem. 273: 26683-26691, 1998. [PubMed: 9756910] [Full Text: https://doi.org/10.1074/jbc.273.41.26683]
Winter, H., Siry, P., Tobiasch, E., Schweizer, J. Sequence and expression of murine type I hair keratins mHa2 and mHa3. Exp. Cell Res. 212: 190-200, 1994. [PubMed: 7514534] [Full Text: https://doi.org/10.1006/excr.1994.1134]
Zhou, P., Byrne, C., Jacobs, J., Fuchs, E. Lymphoid enhancer factor 1 directs hair follicle patterning and epithelial cell fate. Genes Dev. 9: 700-713, 1995. [PubMed: 7537238] [Full Text: https://doi.org/10.1101/gad.9.6.700]