RA | Rubisco activase

Application example

3, 5 and 11 μg of total soluble protein from Arabidopsis thaliana (1), Oryza sativa (2) and Camelina sativa (3) extracted with 50 mM Tricine-NaOH, pH 8, 10 mM EDTA, 1% PVP-40, 20 mM β-mercaptoethanol, 1 mM PMSF and 10 μM leupeptin were separated on 12 % SDS-PAGE and blotted 1h to PVDF. Blots were blocked with 4% non-fat milk in TBS for 1h at room temperature (RT) with agitation. Blot was incubated in the primary antibody at a dilution of 1: 10 000 for over night with agitation. The antibody solution was decanted and the blot was rinsed briefly with H₂O, then washed six times for 15 min in TBS-T at RT with agitation. Blot was incubated in secondary antibody (anti-rabbit IgG alkaline phosphatase conjugated) diluted to 1:3000 in 0.5% non-fat milk in TBS for 2h at RT with agitation. The blot was washed with four changes of TBS-T and developed for 5 min with NBT/BCIP according to the manufacturer’s instructions (Promega). There are two forms of activase (alpha and beta). Alpha is about 46-47 Kda, beta is about 42 kDa what is shown on the blot above.


5 µg of total protein from samples such as Arabidopsis thaliana leaf (1) ,  Hordeum vulgare leaf (2), Zea mays leaf (3),  Nicotiana tabacum (4), Chlamydomonas reinhardtii total cell (5), were extracted with Protein Extraction Buffer PEB (AS08 300). Samples were diluted with 1X sample buffer (NuPAGE LDS sample buffer (Invitrogen) supplemented with 50 mM DTT and heat at 70°C for 5 min and keept on ice before loading. Protein samples were separated on 4-12% Bolt Plus gels,  LDS-PAGE and blotted for 70 minutes to PVDF using tank transfer. Blots were blocked immediately following transfer in 2% blocking reagent or 5% non-fat milk dissolved in 20 mM Tris, 137 mM sodium chloride pH 7.6 with 0.1% (v/v) Tween-20 (TBS-T) for 1h at room temperature with agitation. Blots were incubated in the primary antibody at a dilution of 1: 10 000 (in blocking reagent) for 1h at room temperature with agitation. The antibody solution was decanted and the blot was rinsed briefly twice, and then washed 1x15 min and 3x5 min with TBS-T at room temperature with agitation. Blots were incubated in secondary antibody (anti-rabbit IgG horse radish peroxidase conjugated, recommended secondary antibody AS10 1489, Agrisera) diluted to 1:25 000 in blocking reagent for 1h at room temperature with agitation. The blots were washed as above. The blot was developed for 5 min with chemiluminescent detection reagent according the manufacturers instructions. Images of the blots were obtained using a CCD imager (VersaDoc MP 4000) and Quantity One software (Bio-Rad). Exposure time was 30 seconds.

RA - Ribulose bisphosphate carboxylase/oxygenase activase is an enzyme localized to chloroplasts which activates Rubisco by promoting ATP-dependent conformational changes. Alternative name: RuBisCo activase RCA.