TY - JOUR
T1 - A glycolipid-anchored prion protein is endocytosed via clathrin-coated pits
AU - Shyng, Show Ling
AU - Heuser, John E.
AU - Harris, David A.
PY - 1994/6
Y1 - 1994/6
N2 - The cellular prion protein (PrP(C)) is a glycolipid-anchored, cell surface protein of unknown function, a posttranslationally modified isoform of which PrP(Sc) is involved in the pathogenesis of Creutzfeldt-Jakob disease, scrapie, and other spongiform encephalopathies. We have shown previously that chPrP, a chicken homologue of mammalian PrP(C), constitutively cycles between the cell surface and an endocytic compartment, with a transit time of ~60 min in cultured neuroblastoma cells. We now report that endocytosis of chPrP is mediated by clathrin-coated pits. Immunogold labeling of neuroblastoma cells demonstrates that the concentration of chPrP within 0.05 μm of coated pits is 3-5 times higher than over other areas of the plasma membrane. Moreover, gold particles can be seen within coated vesicles and deeply invaginated coated pits that are in the process of pinching off from the plasma membrane. ChPrP is also localized to coated pits in primary cultures of neurons and glia, and is found in coated vesicles purified from chicken brain. Finally, internalization of chPrP is reduced by 70% after neuroblastoma cells are incubated in hypertonic medium, a treatment that inhibits endocytosis by disrupting clathrin lattices. Caveolae, plasmalemmal invaginations in which several other glycolipid-anchored proteins are concentrated, are not seen in neuroblastoma cells analyzed by thin-section or deep-etch electron microscopy. Moreover, these cells do not express detectable levels of caveolin, a caveolar coat protein. Since chPrP lacks a cytoplasmic domain that could interact directly with the intracellular components of clathrin-coated pits, we propose that the polypeptide chain of chPrP associates with the extracellular domain of a transmembrane protein that contains a coated pit internalization signal.
AB - The cellular prion protein (PrP(C)) is a glycolipid-anchored, cell surface protein of unknown function, a posttranslationally modified isoform of which PrP(Sc) is involved in the pathogenesis of Creutzfeldt-Jakob disease, scrapie, and other spongiform encephalopathies. We have shown previously that chPrP, a chicken homologue of mammalian PrP(C), constitutively cycles between the cell surface and an endocytic compartment, with a transit time of ~60 min in cultured neuroblastoma cells. We now report that endocytosis of chPrP is mediated by clathrin-coated pits. Immunogold labeling of neuroblastoma cells demonstrates that the concentration of chPrP within 0.05 μm of coated pits is 3-5 times higher than over other areas of the plasma membrane. Moreover, gold particles can be seen within coated vesicles and deeply invaginated coated pits that are in the process of pinching off from the plasma membrane. ChPrP is also localized to coated pits in primary cultures of neurons and glia, and is found in coated vesicles purified from chicken brain. Finally, internalization of chPrP is reduced by 70% after neuroblastoma cells are incubated in hypertonic medium, a treatment that inhibits endocytosis by disrupting clathrin lattices. Caveolae, plasmalemmal invaginations in which several other glycolipid-anchored proteins are concentrated, are not seen in neuroblastoma cells analyzed by thin-section or deep-etch electron microscopy. Moreover, these cells do not express detectable levels of caveolin, a caveolar coat protein. Since chPrP lacks a cytoplasmic domain that could interact directly with the intracellular components of clathrin-coated pits, we propose that the polypeptide chain of chPrP associates with the extracellular domain of a transmembrane protein that contains a coated pit internalization signal.
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U2 - 10.1083/jcb.125.6.1239
DO - 10.1083/jcb.125.6.1239
M3 - Article
C2 - 7911471
AN - SCOPUS:0028305135
SN - 0021-9525
VL - 125
SP - 1239
EP - 1250
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 6
ER -