MT1B

MT1B, or metallothionein 1B, is a protein-coding gene in humans that belongs to the metallothionein family of cysteine-rich, metal-binding proteins. The MT1 family comprises several closely related genes, and MT1B is expressed as a small, highly thiol-rich protein capable of binding zinc, copper, and toxic metals such as cadmium through thiolate bonds.

Biochemically, metallothioneins are small, low-molecular-weight proteins with a high content of cysteine residues. MT1B shares this cysteine-rich composition and forms metal-thiolate clusters that sequester metal ions. This allows MT1B to participate in metal ion homeostasis and detoxification, and to contribute to protection against oxidative stress.

Genomic context: In humans, MT1B is part of the MT1 gene cluster on chromosome 16q13, alongside other MT1 family members. MT1B expression is regulated by metal exposure and various cellular stress signals; transcription is often upregulated in response to zinc or cadmium treatment, with tissue-specific patterns.

Expression and function: MT1B is expressed in multiple tissues with higher levels in organs involved in metal handling, such as the liver and kidney, though expression can be detected broadly. Its functions include buffering intracellular metal availability, protecting proteins from metal-induced damage, and modulating metal-dependent enzymatic processes.

Clinical relevance: Altered MT1B expression or polymorphisms have been investigated in relation to metal toxicity and cancer, though the specific roles of MT1B can vary by tissue and context. As with other metallothioneins, MT1B is a focus of ongoing research in toxicology and metalloprotein biology.