T-cadherin GPI-anchor is insufficient for apical targeting in MDCK cells |
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Authors: | Goubaeva Farida Giardina Sarah Yiu Kevin Parfyonova Yelena Tkachuk Vsevolod A Yang Jay |
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Affiliation: | Department of Anesthesiology, Columbia University P & S, 630 West 168th Street, New York, NY 10032, USA. |
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Abstract: | T-cadherin is a 95kDa glycoprotein member of the cadherin family of adhesion molecules attached to the extracellular surface of the cell membrane through a glycosyl-phosphatidylinositol (GPI)-anchor. Whether a T-cadherin ectodomain apical targeting signal or the GPI-anchor itself targets this protein to the apical membrane is not known. Chimeras of the reporter EGFP and T-cadherin have demonstrated that a minimal construct consisting of the C-terminal 25 amino acids including the N690 (omega-site) of T-cadherin was sufficient to GPI-anchor the EGFP protein. However, efficient GPI-anchor with minimal secretion of the protein required an additional 5 residues (omega-1 to omega-5). The GPI-anchored chimeras fractionated to the Triton X-100 detergent insoluble fraction and were released to the cell culture supernatant by phosphoinositide-specific phospho-lipase C digestion. When expressed in MDCK cells, all GPI-anchored chimeras targeted to the basolateral membrane, while the T/N-chimera and the wild-type T-cadherin targeted to the apical membrane. Therefore, T-cadherin is an example of another rare GPI-anchored protein where the anchor itself is not sufficient for apical targeting in MDCK cells. |
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Keywords: | T-cadherin Protein sorting Apical membrane Chimeras GPI-anchor MDCK cells |
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