Missense mutation (G480C) in the CFTR gene associated with protein mislocalization but normal chloride channel activity

Lisa S. Smit, Theresa V. Strong, Daniel J. Wilkinson, Milan Macek, Monique K. Mansoura, Deborah L. Wood, Jeffery L. Cole, Garry R. Cutting, Jonathan A. Cohn, David C. Dawson, Francis S. Collins

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


We have identified a novel CFTR missense mutation associated with a protein trafficking defect in mammalian cells but normal chloride channel properties in a Xenopus oocyte assay. The mutation, a cysteine for glycine substitution at residue 480 (G480C), was detected in a pancreatic Insufficient, African-American, cystic fibrosis (CF) patient. G480C was found on one additional CF chromosome and on none of 220 normal chromosomes, including 160 chromosomes from normal African-American individuals. Western blot analysis and immunofluorescence studies revealed that, in 293T cells, the encoded mutant protein was not fully glycosylated and failed to reach the plasma membrane, suggesting that the G480C protein was subject to defective intracellular processing. However, in Xenopus oocytes, a system in which mutant CFTR proteins are less likely to experience an intracellular processing/trafficking deficit, expression of G480C CFTR was associated with a chloride conductance that exhibited a sensitivity to activation by forskolin and 3-isobutyl-1-methylxanthine (IBMX) that was similar to that of wild-type CFTR. This appears to be the first Identification of a CFTR mutant with a single amino acid substitution in which the sole basis for disease is mislocalization of the protein.

Original languageEnglish (US)
Pages (from-to)269-273
Number of pages5
JournalHuman molecular genetics
Issue number2
StatePublished - Feb 1995
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Genetics(clinical)


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