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Protein expression and distribution of murine calcium‐activated chloride channels 1 and 2 (mCLCA1/2) in epithelia of the gastrointestinal (GI) tract and kidney (Ki)
Author(s) -
Thevenod Frank,
Wittschen Petra,
Torchalski Blazej,
Gruber Achim D.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.938.7
Subject(s) - chloride channel , microbiology and biotechnology , biology , polyclonal antibodies , immunoprecipitation , apical membrane , immunohistochemistry , chemistry , antibody , biochemistry , membrane , immunology
Calcium‐activated chloride channels (CLCA) have been implicated as anion channels, channel regulators and cystic fibrosis phenotype modulators, but their function remains unclear. We generated a polyclonal antibody (pAb 849) against a peptide that is common to mCLCA1/2, has ~70% aa identity with mCLCA3/4, but none with mCLCA5/6. pAb 849 detected mCLCA1 expressed in HEK293 by immunoblotting (IB) and immunoprecipitation, where 125 and 90 kDa bands suggest posttranslational modification. Flag‐tagging of mCLCA1 yielded only a 130 kDa band. pAb 849 cross‐reacted with mCLCA3 in IB with bands at 120, 100 and 75 kDa. Using immunohistochemistry and comparison with mCLCA3 (pAb p3a), mCLCA1/2 specific labelling was found in pancreas acini (apical (AP), zymogen granules (ZG)), but not in ducts. pAb 849 IB of ZG membranes yielded a 130 kDa band. Specific signals were also seen in small ducts of seromucous salivary glands (AP, intracellular (IC)) but not in excretory ducts or acini. Stomach parietal (AP, IC) and jejunal crypt cells (AP) were specifically labelled. Signals in stomach mucous and jejunal goblet cells may be due to mCLCA3 cross‐reactivity. Only AP areas of Ki distal tubules were stained. mCLCA1/2 positive tissues do not express mCLCA4, therefore the data indicate mCLCA1/2 expression in AP membranes of GI and Ki and ZG membranes, but a function as secretory proteins cannot be excluded. Funding: German CFF F04/04