Function: May be involved in cell migration and/or actin cytoskeleton organization. When expressed in keratinocytes, induces changes in cell morphology with transfected cells showing an elongated shape, numerous membrane protrusions, major reorganization of the actin cytoskeleton, increased motility and decreased cell adhesion. Required for normal lung cell proliferation and alveolus formation at birth. Induces platelet aggregation. Does not have any effect on folic acid or amino acid transport. Does not function as a water channel or as a regulator of aquaporin-type water channels. Ref.3 Ref.4 Ref.9 Ref.10 Ref.11
Subcellular location: Membrane; Single-pass type I membrane protein. Cell projection › lamellipodium membrane; Single-pass type I membrane protein. Cell projection › filopodium membrane; Single-pass type I membrane protein. Cell projection › microvillus membrane; Single-pass type I membrane protein. Cell projection › ruffle membrane; Single-pass type I membrane protein. Note: Localized to actin-rich microvilli and plasma membrane projections such as filopodia, lamellipodia and ruffles. Ref.3
Tissue specificity: Detected at high levels in lung and brain, at lower levels in kidney, stomach, liver, spleen and esophagus, and not detected in skin and small intestine. Expressed in epithelial cells of choroid plexus, ependyma, glomerulus and alveolus, in mesothelial cells and in endothelia of lymphatic vessels. Also expressed in stromal cells of peripheral lymphoid tissue and thymic epithelial cells. Detected in carcinoma cell lines and cultured fibroblasts. Expressed at higher levels in colon carcinomas than in normal colon tissue. Ref.3 Ref.4 Ref.10
Induction: Down-regulated by treatment with puromycin aminonucleoside. Ref.4
Post-translational modification: Extensively O-glycosylated. Contains sialic acid residues. O-glycosylation is necessary for platelet aggregation activity. Ref.3 Ref.11The N-terminus is blocked
By similarity.
Disruption phenotype: Mice die at birth of respiratory failure due to a low number of attenuated type I cells, narrow and irregular air spaces, and defective formation of alveolar saccules. Ref.9
Sequence similarities: Belongs to the podoplanin family.
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