Defensin, alpha 3 also known as human alpha defensin 3, human neutrophil peptide 3 (HNP-3) or neutrophil defensin 3 is a human protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that is encoded by the DEFA3 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

. Human alpha defensin 3 belongs to the alpha defensin

Alpha defensin

Alpha defensins are a family of mammalian defensin peptides.Defensins are 2-6 kDa, cationic, microbicidal peptides active against many Gram-negative and Gram-positive bacteria, fungi, and enveloped viruses, containing three pairs of intramolecular disulfide bonds...

 family of antimicrobial

Antimicrobial

An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...

 peptide

Peptide

Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

s.

Function

Defensin

Defensin

Defensins are small cysteine-rich cationic proteins found in both vertebrates and invertebrates. They have also been reported in plants. They are, and function as, host defense peptides. They are active against bacteria, fungi and many enveloped and nonenveloped viruses. They consist of 18-45 amino...

s are a family of microbicidal

Microbicide

Microbicides for sexually transmitted diseases, are pharmacologic agents and chemical substances that are capable of killing or destroying certain microorganisms that commonly cause human infection, for example the human immunodeficiency virus....

 and cytotoxic

Cytotoxicity

Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are a chemical substance, an immune cell or some types of venom .-Cell physiology:...

 peptides thought to be involved in host defense. They are abundant in the granules of neutrophils and also found in the epithelia of mucosal surfaces such as those of the intestine, respiratory tract, urinary tract, and vagina. Members of the defensin family are highly similar in protein sequence and distinguished by a conserved cysteine motif. Several alpha defensin

Alpha defensin

Alpha defensins are a family of mammalian defensin peptides.Defensins are 2-6 kDa, cationic, microbicidal peptides active against many Gram-negative and Gram-positive bacteria, fungi, and enveloped viruses, containing three pairs of intramolecular disulfide bonds...

 genes are clustered on chromosome 8. The protein encoded by this gene, defensin, alpha 3, is found in the microbicidal granules of neutrophils and likely plays a role in phagocyte-mediated host defense. Several alpha defensin genes are clustered on chromosome 8. This gene differs from defensin, alpha 1

Defensin, alpha 1

Defensin, alpha 1 also known as human alpha defensin 1, human neutrophil peptide 1 or neutrophil defensin 1 is a human protein that is encoded by the DEFA1 gene...

by only one amino acid. This gene and the gene encoding defensin, alpha 1 are both subject to copy number variation.

Further reading