The Collagen Family

Abstract

Collagens are the most abundant proteins in mammals. The collagen family comprises 28 members that contain at least one triple-helical domain. Collagens are deposited in the extracellular matrix where most of them form supramolecular assemblies. Four collagens are type II membrane proteins that also exist in a soluble form released from the cell surface by shedding. Collagens play structural roles and contribute to mechanical properties, organization, and shape of tissues. They interact with cells via several receptor families and regulate their proliferation, migration, and differentiation. Some collagens have a restricted tissue distribution and hence specific biological functions. THE COLLAGEN SUPERFAMILYThe collagen superfamily comprises 28 members numbered with Roman numerals in vertebrates (I -XXVIII) ( Table 1). A novel epidermal collagen has been called collagen XXIX (Söder-häll et al. 2007), but the COL29A1 gene was shown to be identical to the COL6A5 gene, and the a1(XXIX) chain corresponds to the a5(VI) chain (Gara et al. 2008). The common structural feature of collagens is the presence of a triple helix that can range from most of their structure (96% for collagen I) to less than 10% (collagen XII). As described in the following discussion, the diversity of the collagen family is further increased by the existence of several a chains, several molecular isoforms and supramolecular structures for a single collagen type, and the use of alternative promoters and alternative splicing.The criteria to name a protein collagen are not well defined and other proteins containing one triple-helical domain (Table 2) are not numbered with a Roman numeral so far and do not belong to the collagen family sensu stricto.

Circular Dichroism Spectroscopy of Collagen Fibrillogenesis: A New Use for an Old Technique

“…Type-I collagen (herein referred to as collagen unless otherwise stated) is composed of two a1 chains and one a2 chain, which associate into a right-handed triple helix (11). These helices further assemble through fibrillogenesis into highly organized fibrils with an evident D-periodic banding every 67 nm along the axis (Fig.…”

“…The 29 members of the collagen family in animals account for~30% of the total body protein content (11). Type-I collagen (herein referred to as collagen unless otherwise stated) is composed of two a1 chains and one a2 chain, which associate into a right-handed triple helix (11).…”

Collagen-Nanoparticles Composites for Wound Healing and Infection Control

“…Currently, at least 28 different types of collagen (Table 2) composed of at least 46 distinct polypeptide chains have been identified in vertebrates, showing remarkable diversity in their molecular and supramolecular organization [30][31][32]. This protein is a natural polymer formed by the polymerization of 20 amino acids, arranged in sequences characteristic for the specific type of collagen molecule, which has a unique triple helix conformational structure.…”

Antibacterial performance of bovine lactoferrin-fish gelatine electrospun membranes

“…Alternative sources of gelatine are being explored to diminish the use of mammalian origin gelatine, due to the reported foodborne transmission of bovine spongiform encephalopathy as well as other prion outbreaks [5,6]. Gelatine is produced through the partial denaturation of collagen, one of the most prominent proteins found in mesodermal tissues and is mainly extracted from bones, skins, tendons and hides [7]. The origin and hydrolysis methodologies employed for collagen denaturation renders different gelatines with distinct physical and chemical properties.…”

“…The origin and hydrolysis methodologies employed for collagen denaturation renders different gelatines with distinct physical and chemical properties. Gelatine type A and type B are obtained from the acid-and alkali-treated precursors, respectively [4,7,8].…”