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The assembly of the major desmosome glycoproteins of Madin‐Darby canine kidney cells
Author(s) -
Penn Elizabeth J.,
Hobson Christine,
Rees David A.,
Magee Anthony I.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81229-3
Subject(s) - desmosome , glycoprotein , calcium , chemistry , biochemistry , biophysics , microbiology and biotechnology , cell culture , cell , biology , genetics , organic chemistry
Madin‐Darby canine kidney (MDCK) cells are unable to form desmosomes when cultured in low‐calcium medium ([Ca 2+ ]<0.1 meq./l), but can be induced to do so by raising the calcium to physiological concentrations (1–2 meq./l). We have previously demonstrated that this block correlated with increased desmosomal protein turnover. Here we have immunoprecipitated the major desmosome glycoproteins [DGI (150 kDa) and DGII/III (120/100 kDa)] from non‐ionic detergent‐soluble and ‐insoluble fractions prepared from metabolically labelled MDCK cells cultured in standard or low‐calcium medium. Pulse‐chase studies showed that both DGI and DGII/III became unextractable in non‐ionic detergent before their arrival at the cell surface, whether cells were grown in standard or low‐calcium medium. The non‐ionic detergent insolubility of these membrane components is therefore a separate step which precedes the formation of morphologically recognisable desmosomes.