Aggrecan is the major proteoglycan in articular cartilage (synthesized by mature chondrocytes) and in perineuronal nets of the CNS. While its precise function around CNS neurons remains obscure, in articular cartilage it contributes to creating the hydrated gel structure of the ECM via its interaction with hyaluronan, link protein, CMPs, COMP and collagen type IX. Deletion of the aggrecan gene causes early disturbances in chondrogenesis and brain defects. Aggrecan is a multimodular molecule whose core protein is composed of three globular domains denoted G1, G2, and G3, a large extended region spanning the portion of the molecule between the globular domains G1 and G2 and containing the majority of the GAG attachment sites and a second GAG-bearing inter-globular domain (IGD) occurs between G2 and G3. The GAG attachment domain between G1 and G2 contains mainly chondroitin sulphate chains (up to 40) and some keratan sulfate chains. The inter-globular G2-G3 domain exclusively bears keratan sulphate chains. The corresponding core protein region of sclera and brain aggrecans do not seem to contain keratan sulphates. The G1 amino-terminal domain of the aggrecan core protein has the same structural motif as link protein and is responsible for the binding of the proteoglycan to hyaluronan and link protein. The G2 globular domain is homologous to the tandem repeats of G1 and of link protein and is crucial for the synthesis and cellular secretion of aggrecan. The G3 globular domain makes up the carboxyl terminus of the core protein and is similarly responsible for post-translational processing of the proteoglycan and its secretion, as well as for its molecular interactions with other cartilage ECM components. Fully glycosylated/glycanated aggrecan of articular cartilage has an average size of 2,400-2,500 kDa, but its Mr may vary with age and the conditions of the cartilage tissue. The non-glycosylated/non-glycanated core protein has an approximate Mr of 240 kDa.

References:
Virgintino D, et all., (2009) Aggrecan isoforms of perineuronal nets identify subsets of parvalbumin and calbindin neurons differentially distributed in cortical layers II-VI of human adult cortex. J. Cell. Mol. Medicine 13, 3151-3173.I161:I164.

Aggrecan is the major proteoglycan in articular cartilage (synthesized by mature chondrocytes) and in perineuronal nets of the CNS. While its precise function around CNS neurons remains obscure, in articular cartilage it contributes to creating the hydrated gel structure of the ECM via its interaction with hyaluronan, link protein, CMPs, COMP and collagen type IX. Deletion of the aggrecan gene causes early disturbances in chondrogenesis and brain defects. Aggrecan is a multimodular molecule whose core protein is composed of three globular domains denoted G1, G2, and G3, a large extended region spanning the portion of the molecule between the globular domains G1 and G2 and containing the majority of the GAG attachment sites and a second GAG-bearing inter-globular domain (IGD) occurs between G2 and G3. The GAG attachment domain between G1 and G2 contains mainly chondroitin sulphate chains (up to 40) and some keratan sulfate chains. The inter-globular G2-G3 domain exclusively bears keratan sulphate chains. The corresponding core protein region of sclera and brain aggrecans do not seem to contain keratan sulphates. The G1 amino-terminal domain of the aggrecan core protein has the same structural motif as link protein and is responsible for the binding of the proteoglycan to hyaluronan and link protein. The G2 globular domain is homologous to the tandem repeats of G1 and of link protein and is crucial for the synthesis and cellular secretion of aggrecan. The G3 globular domain makes up the carboxyl terminus of the core protein and is similarly responsible for post-translational processing of the proteoglycan and its secretion, as well as for its molecular interactions with other cartilage ECM components. Fully glycosylated/glycanated aggrecan of articular cartilage has an average size of 2,400-2,500 kDa, but its Mr may vary with age and the conditions of the cartilage tissue. The non-glycosylated/non-glycanated core protein has an approximate Mr of 240 kDa.

References:
Virgintino D, et all., (2009) Aggrecan isoforms of perineuronal nets identify subsets of parvalbumin and calbindin neurons differentially distributed in cortical layers II-VI of human adult cortex. J. Cell. Mol. Medicine 13, 3151-3173.I161:I164.