A pyrin domain is a protein domain

Protein domain

A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural...

 and a subclass of protein motif known as the death fold

Death fold

The death fold is a tertiary structure motif commonly found in proteins involved in apoptosis or inflammation-related processes. This motif is commonly found in domains that participate in protein-protein interactions leading to the formation of large functional complexes...

; it allows a pyrin domain containing protein to interact with other 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...

s that contain a pyrin domain. It is also known as a PYD or PAAD/DAPIN domain, and is distantly evolutionarily related to the Death domain

Death domain

The death domain is a protein interaction module composed of a bundle of six alpha-helices. DD is a subclass of protein motif known as the death fold and is related in sequence and structure to the death effector domain and the caspase recruitment domain , which work in similar pathways and show...

 family of protein domain

Protein domain

A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural...

s.Proteins containing a pyrin domain are frequently involved in biological processes called inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

 and apoptosis

Apoptosis

Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...

. Proteins that possess a pyrin domain include intracellular microbial sensors called NOD-like receptors, and proteins associated with their function, such as PYCARD

PYCARD

Apoptosis-associated speck-like protein containing a CARD or ASC is a protein that in humans is encoded by the PYCARD gene.This gene encodes an adaptor protein that is composed of two protein–protein interaction domains: a N-terminal PYRIN-PAAD-DAPIN domain and a C-terminal caspase-recruitment...

 and certain fish caspase

Caspase

Caspases, or cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in apoptosis , necrosis, and inflammation....

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