scholarly journals The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Uses its C-Terminus to Regulate the A2B Adenosine Receptor

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Michael J. Watson ◽  
Shernita L. Lee ◽  
Abigail J. Marklew ◽  
Rodney C. Gilmore ◽  
Martina Gentzsch ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Adenosine Receptor ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
A2b Adenosine Receptor ◽  
C Terminus ◽  
Cystic Fibrosis Transmembrane

Multiple endocytic signals in the C-terminal tail of the cystic fibrosis transmembrane conductance regulator

2001 ◽  
Vol 354 (3) ◽  
pp. 561-572 ◽  
Author(s):  
Wei HU ◽  
Marybeth HOWARD ◽  
Gergely L. LUKACS
Keyword(s):  
Cystic Fibrosis ◽  
Interleukin 2 ◽  
Site Directed Mutagenesis ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
C Terminus ◽  
Sorting Signals ◽  
Endocytic Sorting ◽  
Dependent Protein ◽  
Cystic Fibrosis Transmembrane

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent protein kinase (PKA)-activated chloride channel that is localized to the plasma membrane and endosomal compartment. Endosomal targeting of CFTR is attributed to the Tyr1424-based internalization signal, identified in the C-terminal tail of the channel. Mutation of the Tyr1424 residue could partly inhibit the endocytosis of CFTR and its association with the adapter protein AP-2. To reveal additional endosomal targeting signals, site-directed mutagenesis of both a chimaera, composed of a truncated form of interleukin 2 receptor α chain (TacT) and the C-terminal tail of CFTR (Ct), and the full-length CFTR was performed. Morphological and functional assays revealed the presence of multiple internalization motifs at the C-terminus, consisting of a phenylalanine-based motif (Phe1413) and a bipartite endocytic signal, comprising a tyrosine (Tyr1424) and a di-Leu-based (Leu1430-Leu) motif. Whereas the replacement of any one of the three internalization motifs with alanine prevented the endocytosis of the TacT–Ct chimaera, mutagenesis of Phe1413-Leu impaired the biosynthetic processing of CFTR, indicating that Phe1413 is indispensable for the native structure of CFTR. In contrast, replacement of Leu1430-Leu- and Tyr1424-based signals with alanine increased the cell-surface density of both the chimaeras and CFTR in an additive manner. These results suggest that the internalization of CFTR is regulated by multiple endocytic sorting signals.

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