Lecticans, also known as hyalectans, are a family of proteoglycans (a type

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that is attached to chains of negatively charged polysaccharides) that are components of the

extracellular matrix In biology, the extracellular matrix (ECM), also called intercellular matrix, is a three-dimensional network consisting of extracellular macromolecules and minerals, such as collagen, enzymes, glycoproteins and hydroxyapatite that provide s ...

. There are four members of the lectican family: aggrecan,

brevican Brevican core protein is a protein that in humans is encoded by the ''BCAN'' gene. Brevican is a member of the lectican protein family. Brevican is localised to the surface of neurons in the brain A brain is an organ that serves as the cent ...

neurocan Neurocan core protein is a protein that in humans is encoded by the ''NCAN'' gene. Neurocan is a member of the lectican / chondroitin sulfate proteoglycan protein families and consists of neurocan core protein and chondroitin sulfate. It is thou ...

, and

versican Versican is a large extracellular matrix proteoglycan that is present in a variety of human tissues. It is encoded by the ''VCAN'' gene. Versican is a large chondroitin sulfate proteoglycan with an apparent molecular mass of more than 1000kDa. I ...

. Lecticans interact with hyaluronic acid and

tenascin-R Tenascin-R is a protein that in humans is encoded by the ''TNR'' gene. Function Tenascin-R (TNR) is an extracellular matrix protein expressed primarily in the central nervous system. It is a member of the tenascin (TN) gene family, which inclu ...

to form a

ternary complex A ternary complex is a protein complex containing three different molecules that are bound together. In structural biology, ''ternary complex'' can also be used to describe a crystal containing a protein with two small molecules bound, for example ...

Tissue distribution

Aggrecan is a major component of extracellular matrix in cartilage whereas versican is widely expressed in a number of connective tissues including those in

vascular smooth muscle Vascular smooth muscle is the type of smooth muscle that makes up most of the walls of blood vessels. Structure Vascular smooth muscle refers to the particular type of smooth muscle found within, and composing the majority of the wall of blood ve ...

, skin

epithelial Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercell ...

cells, and the cells of central and peripheral

nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...

. The expression of neurocan and brevican is largely restricted to neural tissues.

Structure

All four lecticans contain an N-terminal globular domain (G1 domain) that in turn contains an

immunoglobulin V-set domain V-set domains are Ig-like domains resembling the antibody variable domain. V-set domains are found in diverse protein families, including immunoglobulin light and heavy chains; in several T-cell receptors such as CD2 (Cluster of Differentiation 2) ...

and a

Link domain A Link domain or Link module, also known as Xlink domain (X for extracellular), is a protein domain that binds to hyaluronic acid. It is important in blood cell migration and apoptosis. The link domain is found in some extracellular proteins in ve ...

that binds hyaluronic acid; a long extended central domain (CS) that is modified with covalently attached sulfated

glycosaminoglycan Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharides consisting of repeating disaccharide units (i.e. two-sugar units). The repeating two-sugar unit consists of a uronic sugar and an amino sugar, except in the case ...

chains, and a

C-terminal The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is ...

globular domain (G3 domain) containing of one or more EGF repeats, a

C-type lectin A C-type lectin (CLEC) is a type of carbohydrate-binding protein known as a lectin. The C-type designation is from their requirement for calcium for binding. Proteins that contain C-type lectin domains have a diverse range of functions including c ...

domain and a CRP-like domain. Aggrecan has in addition a globular domain (G2 domain) that is situated between the G1 and CS domains.

References

Protein families {{Transmembranereceptor-stub

Tissue distribution

Structure

See also

References