- Peptide (C)KFLPLKRQAGQPS, corresponding to amino acid residues 200-212 of mouse Orai1 (Accession Q8BWG9). 2nd extracellular loop.
- Mouse B-cell lymphoma (WEHI), rat pancreas and rat spleen lysates (1:200).
- Western blot analysis of rat spleen (lanes 1 and4), rat pancreas (lanes 2 and 5) and mouse B-cell lymphoma (WEHI) (lanes 3 and 6) lysates:1-3. Anti-Orai1 (extracellular) Antibody (#ACC-062), (1:200).
4-6. Anti-Orai1 (extracellular) Antibody, preincubated with Orai1 (extracellular) Blocking Peptide (#BLP-CC062).
- Rat pancreas (1:50).
- WEHI living cells (5-10 µg antibody/0.5 x 106 cells).
- The blocking peptide is not suitable for this application.
- Rat basophilic leukemia (RBL) cells (1:100).
Cytosolic calcium (Ca2+) has long been known to act as a key second messenger in many intracellular pathways including synaptic transmission, muscle contraction, hormonal secretion, cell growth and proliferation1,2. Intracellular Ca2+ levels are controlled by either the influx of Ca2+ through the calcium-release-activated Ca2+ channels (CRAC), or from intracellular stores which gained much attention.
Recently, several key players of the store operated complex have been identified. Orai1 (also known as CRACM1) acts as the store operated Ca2+ channel (SOC) and STIM1, which acts as the endoplasmic reticulum Ca2+ sensor3. The formation of functional channels requires the presence of both Orai1 and STIM1 proteins working as a complex and involves the co-clustering of Orai1 on the plasma membrane with STIM1 on the endoplasmic reticulum6. TRPC1, a member of the transient receptor potential family was also suggested to act as a player in the SOC complex7. In T-cells, Ca2+ entry following activation by antigen-receptor engagement occurs solely through CRAC channels where Orai1 constitutes the pore forming subunit3,8.
Orai1 is a plasma membrane protein with four potential transmembrane domains and intracellular N- and C-terminus. In addition, two mammalian homologs to Orai1 have been identified; Orai2 and Orai33,9. All three, Orai1 Orai2 and Orai3, are capable of forming store operated channels with different magnitudes9.
Species reactivity key:
Expression of Orai1 in mouse optic nerve.A(i-iv). Immunohistochemical staining of mouse optic nerve sections using Anti-Orai1 (extracellular) Antibody (#ACC-062). Orai1 staining (green) is detected in astrocytes and co-localizes with GFAP staining (red) an astrocyte marker. A(v). Immunocytochemical staining of mouse cultured optic nerve cells using Anti-Orai1 (extracellular) Antibody, (green). Note the lack of immunostaining when the antibody is pre-incubated with the blocking peptide (Aiii, inset).Adapted from Papanikolaou, M. et al. (2017) Brain Struct. Funct. 222, 2993. with permission of SPRINGER NATURE.