Lecticans, also known as hyalectans, are a family of
proteoglycan
Proteoglycans are proteins that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s). The point of attachment is a serine (Ser) residue to whic ...
s (a type
protein that is attached to chains of negatively charged
polysaccharide
Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...
s) that are components of the
extracellular matrix. There are four members of the lectican family:
aggrecan
Aggrecan (ACAN), also known as cartilage-specific proteoglycan core protein (CSPCP) or chondroitin sulfate proteoglycan 1, is a protein that in humans is encoded by the ''ACAN'' gene. This gene is a member of the lectican (chondroitin sulfate prote ...
,
brevican,
neurocan, and
versican. Lecticans interact with
hyaluronic acid
Hyaluronic acid (; abbreviated HA; conjugate base hyaluronate), also called hyaluronan, is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. It is unique among glycosaminoglycans ...
and
tenascin-R to form a
ternary complex.
Tissue distribution
Aggrecan is a major component of extracellular matrix in
cartilage
Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
whereas versican is widely expressed in a number of connective tissues including those in
vascular smooth muscle, skin
epithelial cells, and the cells of central and peripheral
nervous system. The expression of neurocan and brevican is largely restricted to neural tissues.
Structure
All four lecticans contain an
N-terminal
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...
globular domain (G1 domain) that in turn contains an
immunoglobulin V-set domain and a
Link domain that binds hyaluronic acid; a long extended central domain (CS) that is modified with covalently attached sulfated
glycosaminoglycan chains, and a
C-terminal globular domain (G3 domain) containing of one or more
EGF repeats, a
C-type lectin domain and a
CRP-like domain. Aggrecan has in addition a globular domain (G2 domain) that is situated between the G1 and CS domains.
See also
*
Hyaladherin
References
Protein families
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