title: Inhibition of capacitative Ca2+ entry into cells by farnesylcysteine analogs.
abstract: Capacitative Ca2+ influx, which occurs in response to mobilization of intracellular Ca2+ stores, is a general feature of many cell types. Although the mechanism of capacitative Ca2+ entry is not known, evidence suggests the involvement of small G proteins that are prenylated on a cysteine residue near their carboxyl termini. We have investigated the actions of farnesyl-cysteine analogs on capacitative Ca2+ influx. Using human embryonic kidney 293 cells, we found that S-farnesylthioacetic acid, N-acetyl-S-farnesyl-L-cysteine, N-pivaloyl-S-farnesyl-L-cysteine, and N-acetyl-S-gernylgernyl-L-cysteine blocked the activation of capacitative Ca2+ influx, whereas N-benzoyl-S-farnesyl-S-cysteine had no effect on capacitative Ca2+ entry. Inhibition by S-farnesylthioacetic acid was concentration dependent (5-20 microM) and specific for Ca2+ influx through non-voltage-gated Ca2+ channels. A single protein band of 26-28 kDa was labeled specifically with a photoaffinity analog of farnesylcysteine. GTP binding to the photoaffinity-labeled band was demonstrated. These findings suggest, but do not prove, that a prenylated substrate, possibly a small G protein, is linked functionally to capacitative Ca2+ entry in human embryonic kidney 293 cells.
authors.affiliation: Department of Molecular and Cellular Toxicology, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
authors.forename: B A
authors.initials: BA
authors.lastname: Gilbert
authors.forename: R R
authors.initials: RR
authors.lastname: Rando
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.forename: A H
authors.initials: AH
authors.lastname: Tashjian
mesh_terms: D000345:Affinity Labels; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008345:Manganese / Q000378:metabolism; D011485:Protein Binding; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000345:Affinity Labels; D008345:Manganese; D019284:Thapsigargin; D006160:Guanosine Triphosphate; D003545:Cysteine; D002118:Calcium