CD44

The protein encoded by this gene is a cell-surface glycoprotein involved in cell-cell interactions, cell adhesion and migration. It is a receptor for hyaluronic acid (HA) and can also interact with other ligands, such as osteopontin, collagens, and matrix metalloproteinases (MMPs). This protein participates in a wide variety of cellular functions including lymphocyte activation, recirculation and homing, hematopoiesis, and tumor metastasis. Transcripts for this gene undergo complex alternative splicing that results in many functionally distinct isoforms, however, the full length nature of some of these variants has not been determined. Alternative splicing is the basis for the structural and functional diversity of this protein, and may be related to tumor metastasis.

CD44 Molecule (Indian Blood Group)

CD44 Molecule (Indian Blood Group); Hematopoietic Cell E- And L-Selectin Ligand; GP90 Lymphocyte Homing/Adhesion Receptor; Chondroitin Sulfate Proteoglycan 8; Extracellular Matrix Receptor III; Heparan Sulfate Proteoglycan; Phagocytic Glycoprotein 1; Hyaluronate Receptor; Hermes Antigen; CD44 Antigen; ECMR-III; HUTCH-I; Epican; CDW44; MDU2; MDU3;

Cell-surface receptor that plays a role in cell-cell interactions, cell adhesion and migration, helping them to sense and respond to changes in the tissue microenvironment (PubMed:16541107, PubMed:19703720, PubMed:22726066).
Participates thereby in a wide variety of cellular functions including the activation, recirculation and homing of T-lymphocytes, hematopoiesis, inflammation and response to bacterial infection (PubMed:7528188).
Engages, through its ectodomain, extracellular matrix components such as hyaluronan/HA, collagen, growth factors, cytokines or proteases and serves as a platform for signal transduction by assembling, via its cytoplasmic domain, protein complexes containing receptor kinases and membrane proteases (PubMed:18757307, PubMed:23589287).
Such effectors include PKN2, the RhoGTPases RAC1 and RHOA, Rho-kinases and phospholipase C that coordinate signaling pathways promoting calcium mobilization and actin-mediated cytoskeleton reorganization essential for cell migration and adhesion (PubMed:15123640).

Cartilage development Source: UniProtKB
Cell adhesion Source: UniProtKB
Cell-cell adhesion Source: UniProtKB
Cell-matrix adhesion Source: UniProtKB
Cell migration Source: UniProtKB
Cellular response to fibroblast growth factor stimulus Source: UniProtKB
Extracellular matrix disassembly Source: Reactome
Extracellular matrix organization Source: Reactome
Hyaluronan catabolic process Source: UniProtKB
Inflammatory response Source: GO_Central
Interferon-gamma-mediated signaling pathway Source: Reactome
Leukocyte migration Source: Reactome
Monocyte aggregation Source: UniProtKB
Negative regulation of apoptotic process Source: UniProtKB
Negative regulation of cysteine-type endopeptidase activity involved in apoptotic process Source: UniProtKB
Negative regulation of DNA damage response, signal transduction by p53 class mediator Source: BHF-UCL
Negative regulation of intrinsic apoptotic signaling pathway in response to DNA damage by p53 class mediator Source: BHF-UCL
Neutrophil degranulation Source: Reactome
Positive regulation of ERK1 and ERK2 cascade Source: BHF-UCL
Positive regulation of heterotypic cell-cell adhesion Source: UniProtKB
Positive regulation of monocyte aggregation Source: BHF-UCL
Positive regulation of peptidyl-serine phosphorylation Source: BHF-UCL
Positive regulation of peptidyl-tyrosine phosphorylation Source: BHF-UCL
Regulation of lamellipodium morphogenesis Source: UniProtKB
T cell activation Source: UniProtKB
Wound healing, spreading of cells Source: UniProtKB

Cell membrane; Microvillus. Colocalizes with actin in membrane protrusions at wounding edges. Co-localizes with RDX, EZR and MSN in microvilli. Localizes to cholesterol-rich membrane-bound lipid raft domains.

Extracellular: 21-649
Helical: 650-670
Cytoplasmic: 671-742

Proteolytically cleaved in the extracellular matrix by specific proteinases (possibly MMPs) in several cell lines and tumors.
N-glycosylated.
O-glycosylated. O-glycosylation contains more-or-less-sulfated chondroitin sulfate glycans, whose number may affect the accessibility of specific proteinases to their cleavage site(s). It is uncertain if O-glycosylation occurs on Thr-637 or Thr-638.
Phosphorylated; activation of PKC results in the dephosphorylation of Ser-706 (constitutive phosphorylation site), and the phosphorylation of Ser-672.