Alternative titles; symbols
HGNC Approved Gene Symbol: KRT33B
Cytogenetic location: 17q21.2 Genomic coordinates (GRCh38): 17:41,363,498-41,369,813 (from NCBI)
See KRTHA1 (601077) for general information on hair keratins.
By screening a human scalp cDNA library with a mouse Ha2 (see 602760) cDNA, Rogers et al. (1994) cloned a partial cDNA encoding KRTHA3B, which they named HA3II. The cDNA has an open reading frame that encodes 362 amino acids, including a predicted 37-amino acid C-terminal domain; the authors estimated that the cDNA lacks the coding sequence for 43 N-terminal residues. The partial HA3II isoform differs from the HA3I isoform (KRTHA3A; 602761) by 24 amino acids, 8 of which are in the center of the C-terminal domain. Using PCR, sequence, and Southern blot analyses, Rogers et al. (1994) demonstrated that HA3I and HA3II are distinct, single-copy genes.
Rogers et al. (1998) reported that the deduced KRTHA3B protein has 405 amino acids and shares 93.3% amino acid sequence identity with KRTHA3A. By RT-PCR, Rogers et al. (1998) showed that KRTHA3B is expressed in the human hair follicle. See Langbein et al. (1999) for further details on the expression pattern of the KRTHA3B gene in the hair follicle.
Rogers et al. (1998) reported that the KRTHA3B gene contains 7 exons.
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 (602764)--KRTHA2 (602760)--orphan exon--KRTHA8 (604542)--KRTHA7 (604541)--pseudogene--KRTHA1--KRTHA4 (602763)--KRTHA3B--KRTHA3A--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., Schweizer, J., Krieg, T., Winter, H. A novel human type I hair keratin gene: evidence for two keratin hHa3 isoforms. Molec. Biol. Rep. 20: 155-161, 1994. [PubMed: 7565656] [Full Text: https://doi.org/10.1007/BF00990548]
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]