TY - JOUR
T1 - A minimal isoform of the TMEM16A protein associated with chloride channel activity
AU - Ferrera, Loretta
AU - Scudieri, Paolo
AU - Sondo, Elvira
AU - Caputo, Antonella
AU - Caci, Emanuela
AU - Zegarra-Moran, Olga
AU - Ravazzolo, Roberto
AU - Galietta, Luis J V
PY - 2011/9
Y1 - 2011/9
N2 - TMEM16A protein, also known as anoctamin-1, has been recently identified as an essential component of Ca2+-activated Cl- channels. We previously reported the existence of different TMEM16A isoforms generated by alternative splicing. In the present study, we have determined the functional properties of a minimal TMEM16A protein. This isoform, called TMEM16A(0), has a significantly shortened amino-terminus and lacks three alternative segments localized in the intracellular regions of the protein (total length: 840 amino acids). TMEM16A(0) expression is associated with Ca2+-activated Cl- channel activity as measured by three different functional assays based on the halide-sensitive yellow fluorescent protein, short-circuit current recordings, and patch-clamp technique. However, compared to a longer isoform, TMEM16(abc) (total length: 982 amino acids), TMEM16A(0) completely lacks voltage-dependent activation. Furthermore, TMEM16A(0) and TMEM16A(abc) have similar but not identical responses to extracellular anion replacement, thus suggesting a difference in ion selectivity and conductance. Our results indicate that TMEM16A(0) has the basic domains required for anion transport and Ca 2+-sensitivity. However, the absence of alternative segments, which are present in more complex isoforms of TMEM16A, modifies the channel gating and ion transport ability.
AB - TMEM16A protein, also known as anoctamin-1, has been recently identified as an essential component of Ca2+-activated Cl- channels. We previously reported the existence of different TMEM16A isoforms generated by alternative splicing. In the present study, we have determined the functional properties of a minimal TMEM16A protein. This isoform, called TMEM16A(0), has a significantly shortened amino-terminus and lacks three alternative segments localized in the intracellular regions of the protein (total length: 840 amino acids). TMEM16A(0) expression is associated with Ca2+-activated Cl- channel activity as measured by three different functional assays based on the halide-sensitive yellow fluorescent protein, short-circuit current recordings, and patch-clamp technique. However, compared to a longer isoform, TMEM16(abc) (total length: 982 amino acids), TMEM16A(0) completely lacks voltage-dependent activation. Furthermore, TMEM16A(0) and TMEM16A(abc) have similar but not identical responses to extracellular anion replacement, thus suggesting a difference in ion selectivity and conductance. Our results indicate that TMEM16A(0) has the basic domains required for anion transport and Ca 2+-sensitivity. However, the absence of alternative segments, which are present in more complex isoforms of TMEM16A, modifies the channel gating and ion transport ability.
KW - Alternative splicing
KW - Chloride channel
KW - Intracellular calcium
KW - Patch-clamp
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U2 - 10.1016/j.bbamem.2011.05.017
DO - 10.1016/j.bbamem.2011.05.017
M3 - Article
C2 - 21645494
AN - SCOPUS:79959962144
VL - 1808
SP - 2214
EP - 2223
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
SN - 0005-2736
IS - 9
ER -