Expression of truncated transient receptor potential protein 1alpha (Trp1alpha ): evidence that the Trp1 C terminus modulates store-operated Ca2+ entry

J Biol Chem. 2000 Nov 24;275(47):36483-6. doi: 10.1074/jbc.C000529200.


Transient receptor potential protein 1 (Trp1) has been proposed as a component of the store-operated Ca(2+) entry (SOCE) channel. However, the exact mechanism by which Trp1 is regulated by store depletion is not known. Here, we examined the role of the Trp1 C-terminal domain in SOCE by expressing hTrp1alpha lacking amino acids 664-793 (DeltaTrp1alpha) or full-length hTrp1alpha in the HSG (human submandibular gland) cell line. Both carbachol (CCh) and thapsigargin (Tg) activated sustained Ca(2+) influx in control (nontransfected), DeltaTrp1alpha-, and Trp1alpha-expressing cells. Sustained [Ca(2+)](i), following stimulation with either Tg or CCh in DeltaTrp1alpha-expressing cells, was about 1.5-2-fold higher than in Trp1alpha-expressing cells and 4-fold higher than in control cells. Importantly, (i) basal Ca(2+) influx and (ii) Tg- or CCh-stimulated internal Ca(2+) release were similar in all the cells. A similar increase in Tg-stimulated Ca(2+) influx was seen in cells expressing Delta2Trp1alpha, lacking the C-terminal domain amino acid 649-793, which includes the EWKFAR sequence. Further, both inositol 1,4,5-trisphosphate receptor-3 and caveolin-1 were immunoprecipitated with DeltaTrp1alpha and Trp1alpha. In aggregate, these data suggest that (i) the EWKFAR sequence does not contribute significantly to the Trp1-associated increase in SOCE, and (ii) the Trp1 C-terminal region, amino acids 664-793, is involved in the modulation of SOCE.

MeSH terms

  • Calcium / metabolism*
  • Calcium Channels / biosynthesis*
  • Calcium Channels / chemistry
  • Calcium Channels / metabolism
  • Carbachol / pharmacology
  • Caveolin 1
  • Caveolins / metabolism
  • Cells, Cultured
  • Humans
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Inositol 1,4,5-Trisphosphate Receptors
  • Microscopy, Confocal
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Structure-Activity Relationship
  • TRPC Cation Channels
  • Thapsigargin / pharmacology
  • Transfection


  • CAV1 protein, human
  • Calcium Channels
  • Caveolin 1
  • Caveolins
  • ITPR1 protein, human
  • Inositol 1,4,5-Trisphosphate Receptors
  • Receptors, Cytoplasmic and Nuclear
  • TRPC Cation Channels
  • transient receptor potential cation channel, subfamily C, member 1
  • Thapsigargin
  • Inositol 1,4,5-Trisphosphate
  • Carbachol
  • Calcium