Cell Signaling Technology

Product Pathways - Apoptosis

Phospho-Bim (Ser55) Antibody #4550

Applications Reactivity Sensitivity MW (kDa) Source
W M (H) (R) Endogenous 26 Rabbit

Applications Key:  W=Western Blotting
Reactivity Key:  H=Human  M=Mouse  R=Rat
Species cross-reactivity is determined by western blot. Species enclosed in parentheses are predicted to react based on 100% sequence homology.

Protocols

Specificity / Sensitivity

Phospho-Bim (Ser55) Antibody detects endogenous levels of mouse Bim protein only when phosphorylated at Ser55. This site is conserved in rat (Ser55) and human (Ser59) but phosphorylation has not been detected in these species.

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Ser55 of mouse Bim. Antibodies were purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from A20 cells, untreated or TPA-treated for 30 minutes, using Phospho-Bim (Ser55) Antibody (upper) or Bim Antibody #2819 (lower).

Background

Bim/Bod is a pro-apoptotic protein belonging to the BH3-only group of Bcl-2 family members including Bad, Bid, Bik, Hrk, and Noxa that contain a BH3 domain but lack other conserved BH1 or BH2 domains (1,2). Bim induces apoptosis by binding to and antagonizing anti-apoptotic members of the Bcl-2 family. Interactions have been observed with Bcl-2, Bcl-xL, Mcl-1, Bcl-w, Bfl-1, and BHRF-1 (1,2). Bim functions in regulating apoptosis associated with thymocyte negative selection and following growth factor withdrawal, during which Bim expression is elevated (3-6). Three major isoforms of Bim are generated by alternative splicing: BimEL, BimL, and BimS (1). The shortest form, BimS, is the most cytotoxic and is generally only transiently expressed during apoptosis. The BimEL and BimL isoforms may be sequestered to the dynein motor complex through an interaction with the dynein light chain and released from this complex during apoptosis (7). Apoptotic activity of these longer isoforms may be regulated by phosphorylation (8,9). Environmental stress triggers Bim phosphorylation by JNK and results in its dissociation from the dynein complex and increased apoptotic activity.

Survival factor induced ERK activation leads to phosphorylation of mouse Bim at Ser55, which inhibits its pro-apoptotic activity and association with Bax (10).

  1. O'Connor, L. et al. (1998) EMBO J 17, 384-95.
  2. Hsu, S.Y. et al. (1998) Mol Endocrinol 12, 1432-40.
  3. Bouillet, P. et al. (2002) Nature 415, 922-6.
  4. Whitfield, J. et al. (2001) Neuron 29, 629-43.
  5. Dijkers, P.F. et al. (2000) Curr Biol 10, 1201-4.
  6. Ley, R. et al. (2003) J Biol Chem 278, 18811-6.
  7. Puthalakath, H. et al. (1999) Mol Cell 3, 287-96.
  8. Lei, K. and Davis, R.J. (2003) Proc Natl Acad Sci U S A 100, 2432-7.
  9. Putcha, G.V. et al. (2003) Neuron 38, 899-914.
  10. Harada, H. et al. (2004) Proc Natl Acad Sci USA 101, 15313-15317.

Application References

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Companion Products

For Research Use Only. Not For Use In Diagnostic Procedures.

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