T-cadherin GPI-anchor is insufficient for apical targeting in MDCK cells.
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.
Goubaeva
Farida
F
Department of Anesthesiology, Columbia University P & S, 630 West 168th Street, New York, NY 10032, USA.
Giardina
Sarah
S
Yiu
Kevin
K
Parfyonova
Yelena
Y
Tkachuk
Vsevolod A
VA
Yang
Jay
J
D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D002460:Cell Line; D004285:Dogs; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D007668:Kidney / Q000166:cytology* / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology*
D015820:Cadherins; D017261:Glycosylphosphatidylinositols; C099972:H-cadherin