Recombinant Arabidopsis thaliana Thylakoid membrane phosphoprotein 14 kDa, chloroplastic (TMP14)
Description
Definition and Basic Properties
Recombinant Arabidopsis thaliana Thylakoid Membrane Phosphoprotein 14 kDa, Chloroplastic (TMP14) is a nuclear-encoded, chloroplast-targeted protein expressed in Arabidopsis thaliana. It is a transmembrane phosphoprotein with a molecular weight of ~14 kDa, initially identified in thylakoid membranes and later characterized for its roles in photosynthesis and membrane architecture .
2.1. Amino Acid Sequence and Phosphorylation
The mature protein (46–174 residues) contains a conserved sequence:
AAKATAYCRKIVRNVVTRATTEVGEAPATTTEAETTELPEIVKTAQEAWEKVDDKYAIGSLAFAGVVALWGSAGMISAIDRLPLVPGVLELVGIGYTGWFTYKNLVFKPDREALFEKVKS... . Phosphorylation occurs exclusively at Thr residues, as demonstrated by in vivo studies .
| Phosphorylation Site | Functional Implication |
|---|---|
| N-terminal Thr | Potential role in redox-regulated protein interactions |
3.1. Thylakoid Membrane Architecture
TMP14/CURT1B forms oligomeric complexes that induce membrane curvature, enabling the formation of grana stacks and stroma lamellae. Knockout mutants exhibit flattened, lobe-like thylakoids with reduced photosynthetic efficiency, while overexpression promotes taller grana stacks .
3.2. Phosphorylation and Redox Regulation
TMP14 is one of three novel phosphoproteins identified in Arabidopsis thylakoids, with phosphorylation linked to redox-regulated kinase activity (e.g., STN7/STN8) . Unlike PSI-L or LHCII, its phosphorylation status remains stable in state transitions (state 1 vs. state 2) .
Controversies and Nomenclature Clarification
TMP14 was transiently misclassified as a PSI subunit (PsaP) but later redefined as CURT1B, a structural protein governing thylakoid ultrastructure . This reclassification emphasizes its role in membrane remodeling rather than direct electron transfer .
References
Product Specs
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Target Background
- Research indicates that the four CURVATURE THYLAKOID1 (CURT1) proteins – CURT1A (At4g01150), CURT1B (At2g46820), CURT1C (At1g52220), and CURT1D (At4g38100) – form oligomers and are highly concentrated at grana margins. PMID: 23839788
- Studies have demonstrated the exclusive localization of TMP14 in plant photosystem I (PSI), identifying TMP14 (also known as PSI-P) as a novel subunit of PSI. PMID: 16109415
