CLPR2 Antibody

Target Protein: ClpR2

ClpR2 is a non-catalytic subunit of the chloroplast ClpPRS protease complex, essential for maintaining protein homeostasis in chloroplasts . Unlike catalytic ClpP subunits, ClpR2 lacks the Ser-His-Asp catalytic triad but plays a structural role in stabilizing the protease complex . It is encoded by the nuclear gene CLPR2 (AT1G12410 in Arabidopsis thaliana) and post-translationally imported into chloroplasts .

Functional Studies in Arabidopsis Mutants

The CLPR2 antibody has been instrumental in characterizing T-DNA insertion mutants (clpr2-1):

• Phenotypic defects: Pale-green leaves, delayed shoot development, and reduced chloroplast size .

• Molecular insights:

  • 5-fold reduction in ClpR2 accumulation destabilizes the entire ClpPRS complex .

  • Accumulation of unprocessed light-harvesting complex II proteins in thylakoids .

  • Upregulation of thylakoid proteases (e.g., FtsH, Deg) and stromal chaperones (ClpC1/2) .

Role in Chloroplast Proteostasis

• Protein quality control: CLPR2 deficiency leads to increased plastoglobules and carotenoid content, indicating impaired thylakoid membrane turnover .

• Photosystem II dysfunction: Partial inactivation observed in mutants, linked to defective protein processing .

Key Validation Studies

• Western blot analysis: Detected ClpR2 in complemented clpr2-1 mutants expressing ClpR2:His6 fusion proteins .

• Subcellular localization: Confirmed chloroplast stromal localization using fractionation assays .

Limitations and Cross-Reactivity

• Non-reactive species: Maize (Zea mays) .

• Cross-reactivity: Predicted in Brassica napus and Gossypium arboreum but requires empirical validation .