Bcl-xL (human, recombinant)

Bcl-xL is an anti-apoptotic member of the Bcl-2 family of proteins and is the long isoform of the apoptosis regulator Bcl-x formed by alternative splicing.¹ Bcl-xL is composed of a C-terminal helix that acts as a membrane anchor and four highly conserved Bcl-2 homology (BH) domains.² The BH1, BH2, and BH3 domains form a hydrophobic cleft that facilitates Bcl-xL heterodimerization with the pro-apoptotic proteins Bax and Bak, resulting in their inhibition, whereas the BH4 domain regulates intracellular calcium levels.^2,3 Bcl-xL is highly expressed during embryogenesis and neuron and lymphocyte development and is primarily localized to the mitochondrial outer membrane.⁴ It inhibits the intrinsic apoptotic pathway by inhibiting Bax- or Bak-induced pore formation in the outer mitochondrial membrane, maintaining the mitochondrial membrane potential, and preventing the release of cytochrome c into the cytosol and the induction of apoptosis.⁵ Increased Bcl-xL levels promote cell migration, invasion, and capillary-like structure formation in MXL90 melanoma and AXL42 glioblastoma cancer cells, which endogenously express high levels of Bcl-xL.⁶ Mutation of serine 62 (S62A) in Bcl-xL mimics its phosphorylation and abolishes apoptosis induced by the microtubule inhibitor vinblastine (Item No. 11762) in KB-3 cells.⁷ Cayman's Bcl-xL (human, recombinant) protein can be used for binding assay applications. This protein consists of 212 amino acids and has a calculated molecular weight of 25.2 kDa. By SDS-PAGE, under reducing conditions, the apparent molecular mass of the protein is approximately 32 kDa.

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1. Stevens, M., and Oltean, S. Modulation of the apoptosis gene Bcl-x function through alternative splicing. Front. Genet. 10, 804 (2019).

2. Tsujimoto, Y., and Shimizu, S. Bcl-2 family: Life-or-death switch. FEBS Lett. 466(1), 6-10 (2000).

3. Gabellini, C., Trisciuoglio, D., and Del Bufalo, D. Non-canonical roles of Bcl-2 and Bcl-xL proteins: Relevance of BH₄ domain. Carcinogenesis 38(6), 579-587 (2017).

4. Opferman, J.T., and Kothari, A. Anti-apoptotic BCL-2 family members in development. Cell Death Differ. 25(1), 37-45 (2018).

5. Chen, Y., Aaon, M.A., Hsu, Y.-T., et al. Bcl-XL regulates mitochondrial energetis by stabilizing the inner membrane potential. J. Cell Biol. 195(2), 263-276 (2011).

6. Trisciuoglio, D., Tupone, M.G., Desideri, M., et al. BCL-XL overexpression promotes tumor progression-associated properties. Cell Death Dis. 8(12), 3216 (2017).

7. Upreti, M., Galitovskaya, E.N., Chu, R., et al. Identification of the major phosphorylation site in Bcl-xL induced by microtubule inhibitors and analysis of its functional significance. J. Biol. Chem 283(51), 35517-35525 (2008).