Connective tissue is formed by CELLS EXTRACELLULAR MATRIX

Connective tissue is formed by: CELLS + EXTRACELLULAR MATRIX (intercellular matrix)

Cells of connective tissue 1. Fibroblasts. 2. Chondroblasts (cartilage). 3. Osteoblasts (bone). 4. Odontoblasts (tooth). These cells synthetise extracellular matrix.

Extracellular matrix Consists 0 f FIBRILLAR PROTEINS (collagen, elastin) GLYCOPROTEINS (e. g. fibronectin, laminin) GLYCOSAMINOGLYCANS AND PROTEOGLYCANS Structural proteins collagen ------ firmness Elastin------- elasticity

COLLAGENS The most abundant proteins in mammals. They form approximately 25 % of all body proteins. Collagen has a characteristic amino acid composition and their specific sequence. Primary structure of collagen Consists of 1 -Fundamental AA: Glycine and Proline 2 -Derived and Hydroxylysine Collagen has a characteristic AA sequence as it is formed of Triplet –Gly (glycine)– X (proline) – Y (hydroxypoline or hydroxylisine) – Every third AA is GLYCINE. On the next position frequently PROLINE. On the third position frequently hydroxyproline, ev. hydroxylysine

Glycosaminoglycans Polysaccharide chain of GAG is formed by repeating disaccharide units. [URONIC ACID – AMINO SUGAR]n OR [MONOSACCHARIDE - SULFONATED AMINO SUGAR]n PROTEOGLYCANS Proteoglycans are formed by glycosaminoglycans, attached to core protein by: 1 -O-glycoside bond Through the reaction of -OH group of serine or threonineof the core protein with trisaccharide (Xyl-Gal). 2 -N-glycoside bond. Through the reaction of amide nitrogen of asparagines.

ADHESION GLYCOPROTEINS Ensure specific interactions between cells and molecules of extracellular matrix. Functions of adhesion glycoproteins▫ attachment of cells to extracellular matrix organization of the compounds of extracellular matrix Long flexible molecules with several binding sitesfor collagen, other matrix proteins, polysaccharides and cell receptors Examples: fibronectin-laminin-osteonectin-chondronectin