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CD44

Developmental stage

Expressed in the developing retina between 16 and 19 weeks post-conception, specifically in the outer neuroblastic zone, inner neuroblastic zone, interphotoreceptor zone and the retinal pigment epithelium (at protein level).

Domain

The lectin-like LINK domain is responsible for hyaluronan binding.

Function

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).

Post-translational modifications

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.

Tissue specificity

Isoform 10 (epithelial isoform) is expressed by cells of epithelium and highly expressed by carcinomas. Expression is repressed in neuroblastoma cells.

Cellular localization

  • Cell membrane
  • Single-pass type I membrane protein
  • Cell projection
  • 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.

Alternative names

  • CD44 antigen
  • CDw44
  • Epican
  • Extracellular matrix receptor III
  • GP90 lymphocyte homing/adhesion receptor
  • HUTCH-I
  • Heparan sulfate proteoglycan
  • Hermes antigen
  • Hyaluronate receptor
  • Phagocytic glycoprotein 1
  • Phagocytic glycoprotein I
  • ECMR-III
  • PGP-1
  • PGP-I
  • MDU3
  • CD44
  • LHR
  • MDU2
  • MIC4

Target type

Proteins

Primary research area

Oncology

Other research areas

  • Immuno-oncology
  • Immunology & Infectious Disease

Molecular weight

81538Da