PsbI | Small subunit I of PSII

Chlamydomonas reinhardii, Synechcococcus sp. PCC7942

Application example

2 µg of total protein from (1) Arabidopsis thaliana leaf extracted with Protein Extration Buffer, PEB (AS08 300), (2) Hordeum vulgare leaf extracted with PEB, (3) Chlamydomonas reinhardtii total cell extracted with PEB, (4) Synechococcus sp. 7942 total cell extracted with PEB,were separated on 4-12% NuPage (Invitrogen) LDS-PAGE and blotted 1h to PVDF. Blots were blocked immediately following transfer in 2% blocking reagent 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 for 1h at room temperature with agitation. The antibody solution was decanted and the blot was rinsed briefly twice, then washed once for 15 min and 3 times for 5 min in TBS-T at room temperature with agitation. Blots were incubated in secondary antibody (anti-rabbit IgG horse radish peroxidase conjugated) diluted to 1:50 000 in 2% blocking solution for 1h at room temperature with agitation. The blots were washed as above and developed for 5 min with chemiluminescent detection reagent according the manufacturers instructions. Images of the blots were obtained using a CCD imager (FluorSMax, Bio-Rad) and Quantity One software (Bio-Rad). Exposure time was 3 seconds.

The PsbI protein, previously named the 4.8-kDa protein, is encoded by the plastome. PsbI is a universal component of PSII and is highly conserved (e.g. there is 71% amino acid identicality between the Arabidopsis and Synechocystis 6803 proteins). The protein contains 36 to 38 amino acids in most species, with molecular masses ranging between 4.1 and 4.5 kDa. Synonymes: PSII-I, PSII 4.8 kDa protein