Keratin, type I cuticular Ha3-I is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

that in humans is encoded by the ''KRT33A''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

. The protein encoded by this gene is a member of the

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hoove ...

gene family. It is one of the type I hair keratin genes which are clustered in a region of

chromosome 17 Chromosome 17 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 17 spans more than 84 million base pairs (the building material of DNA) and represents between 2.5 and 3% of the total DN ...

q21.2 and have the same direction of transcription. As a type I hair keratin, it is an acidic protein which heterodimerizes with type II keratins to form hair and nails. There are two isoforms of this protein, encoded by two separate genes, ''KRT33A'' (this gene) and '' KRT33B''.

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Further reading