Syndecan-4

SDC4
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	1EJP, 1EJQ, 1OBY, 1YBO
Identifiers
Aliases	SDC4, SYND4, syndecan 4
External IDs	OMIM: 600017; MGI: 1349164; HomoloGene: 31121; GeneCards: SDC4; OMA:SDC4 - orthologs
Gene location (Human)
Chr.	Chromosome 20 (human)
End	45,348,424 bp
Gene location (Mouse)
Chr.	Chromosome 2 (mouse)
End	164,285,807 bp
RNA expression pattern
	Top expressed in
	olfactory zone of nasal mucosa; ; nasal epithelium; ; cartilage tissue; ; beta cell; ; epithelium of bronchus; ; bronchial epithelial cell; ; skin of abdomen; ; skin of leg; ; external globus pallidus; ; human kidney;
	Top expressed in
	vestibular membrane of cochlear duct; ; gallbladder; ; lacrimal gland; ; blastocyst; ; ciliary body; ; utricle; ; ascending aorta; ; left lobe of liver; ; superior surface of tongue; ; aortic valve;
	More reference expression data
	More reference expression data
Gene ontology
Molecular function	fibronectin binding; protein binding; thrombospondin receptor activity; protein kinase C binding; identical protein binding;
Cellular component	integral component of membrane; membrane; focal adhesion; plasma membrane; integral component of plasma membrane; extracellular region; lysosomal lumen; Golgi lumen; membrane raft; costamere; extracellular exosome; cell surface;
Biological process	glycosaminoglycan metabolic process; ureteric bud development; inner ear receptor cell stereocilium organization; positive regulation of extracellular exosome assembly; wound healing; retinoid metabolic process; neural tube closure; glycosaminoglycan catabolic process; glycosaminoglycan biosynthetic process; positive regulation of focal adhesion assembly; positive regulation of exosomal secretion; regulation of fibroblast migration; positive regulation of stress fiber assembly; positive regulation of protein kinase activity; signal transduction; negative regulation of T cell proliferation; leukocyte migration; cell migration;
	Sources:Amigo / QuickGO
Orthologs
	6385
	20971
	ENSG00000124145
	ENSMUSG00000017009
	P31431
	O35988
	NM_002999
	NM_011521
	NP_002990
	NP_035651
	Wikidata
View/Edit Human	View/Edit Mouse

Syndecan-4 is a protein that in humans is encoded by the SDC4 gene. Syndecan-4 is one of the four vertebrate syndecans and has a molecular weight of ~20 kDa. Syndecans are the best-characterized plasma membrane proteoglycans. Their intracellular domain of membrane-spanning core protein interacts with actin cytoskeleton and signaling molecules in the cell cortex. Syndecans are normally found on the cell surface of fibroblasts and epithelial cells. Syndecans interact with fibronectin on the cell surface, cytoskeletal and signaling proteins inside the cell to modulate the function of integrin in cell-matrix adhesion. Also, syndecans bind to FGFs and bring them to the FGF receptor on the same cell. As a co-receptor or regulator, mutated certain proteoglycans could cause severe developmental defects, like disordered distribution or inactivation of signaling molecules.

Syndecans have similar structural features:

Attach to heparan sulfate chains – interacting factors (e.g. Matrix molecules, growth factors, and enzymes)
Chondroitin sulfate chain
Transmembrane domain – self-association
C1 domain – actin-association cytoskeleton
Variable domain – syndecan-specific
C2 domain – attach to PDZ proteins

Syndecans normally form homodimers or multimers. Their biological function includes cell growth regulation, differentiation, and adhesion. Syndecan-4 has more widespread distribution than other syndecans and it is the only syndecan that has been found consistently in focal adhesions.