Family

Tropoelastin (IPR003979)

Short name: Tropoelastin

Family relationships

None.

Description

Tropoelastin is the precursor to the elastin molecule. Elastin aggregates are responsible for the stretch properties of skin, arterial walls and ligaments, and elastin is implicated in several hereditary diseases, including cutis laxa (where the elasticity of the skin is lost) and elastoderma (similar to cutis laxa but with grape-like accumulations of elastin in the dermis). The unusual and highly characteristic amino acid composition of this protein accounts for its great hydrophobicity. It contains one-third glycine amino acids and several lysine derivatives that serve as covalent cross-links between protein monomers. Elastin is thus a three-dimensional network with 60-70 amino acids between two cross-linking points. This molecular architecture is determinant for its elastic properties, insolubility and resistance to proteolysis.

Normally, the elastin gene contains 36 exons, and this structure allows the formation of stable isoforms by alternative splicing. The 3-dimensional structure of elastin is currently unknown and was originally thought to be an amorphous polymer. This is consistent with the theory of rubber elasticity, which requires the resting state of the protein to be of higher disorder (entropy) than the extended state [PMID: 10216959].

More recent studies show the presence of helical and other secondary structures [PMID: 5684878], and the elasticity theory has been amended to involve, in the resting state, secondary structure elements in chaotic motion. In the extended state of the protein, the secondary structures align to form an ordered structure together with neighbouring molecules [PMID: 10216959]. Tropoelastin consists mainly of repetitive elements of four, five, six and nine hydrophobic residues [PMID: 2272748]. The five, six and nine residue repeats function as binding sites for fibroblasts during chemotaxis (the hexapeptide and nonapeptide repeats competing for the same receptor) [PMID: 3345315]. The hexapeptide repeat is also known to bind calcium ions.

The formation of the elastin fibre is a complicated process, involving the binding of a chaperone to the precursor to prevent aggregation in the cell, followed by migration out of the cell, whereupon the chaperone disassociates. The tropoelastin molecules then cross-link to each other using deaminated lysine residues, the microfibril structures functioning as a scaffold [PMID: 10216959].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005201 extracellular matrix structural constituent

Cellular Component

GO:0005578 proteinaceous extracellular matrix

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PRINTS