Incorporation of leucocyte GPI-anchored proteins and protein tyrosine kinases into lipid-rich membrane domains of COS-7 cells.
Several human leucocyte surface glycoproteins and two lymphoid protein kinases were transiently expressed in monkey COS-7 fibroblastoid cells. All glycosylphospha-tidylinositol (GPI)-anchored proteins (CD14, CD16B, CD48, CD59, CD87 and GPI-anchored versions of CD2 and CD25) and protein tyrosine kinase (PTK) Lck but not transmembrane proteins (CD2, CD4, CD5, CD6, CD8) and PTK ZAP-70 were in part localized in buoyant, lipid-rich, detergent-resistant membrane GPI-microdomains of the COS cells. Endogenous GPI-microdomains of COS cells appear to be, in contrast to those present in leucocytes, essentially devoid of associated PTKs. Our results indicate that GPI-anchor is sufficient to target proteins to these membrane specializations even if expressed ectopically. Moreover, the N-terminal double acylation of the PTK Lck appears to be functional also in COS cells and targets the enzyme to the membrane GPI-microdomains implicated in receptor signalling.
Cebecauer
M
M
Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Cerný
J
J
Horejsí
V
V
D000215:Acylation; D000818:Animals; D018801:CD2 Antigens / Q000235:genetics / Q000378:metabolism; D018957:CD59 Antigens / Q000235:genetics / Q000378:metabolism; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism*; D015870:Gene Expression; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006801:Humans; D007962:Leukocytes / Q000737:chemistry*; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000235:genetics / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D015375:Receptors, Interleukin-2 / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D051746:ZAP-70 Protein-Tyrosine Kinase
D018801:CD2 Antigens; D018957:CD59 Antigens; D017261:Glycosylphosphatidylinositols; D008563:Membrane Lipids; D008565:Membrane Proteins; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human