Q9F1K9: Photosystem II reaction center protein K (psbK)

Photosystem II reaction center protein K (psbK) is a 46-residue protein from Thermosynechococcus vestitus (strain NIES-2133 / IAM M-273 / BP-1). This is its AlphaFold structure prediction, created 1 Aug 2025. UniProt accession: Q9F1K9.

Gene: psbK
Organism: Thermosynechococcus vestitus (strain NIES-2133 / IAM M-273 / BP-1)
Length: 46 residues
Mean pLDDT: 92.9
Model: AF-Q9F1K9-F1 v6
Model created: 1 Aug 2025
PDB structures: 65

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Model confidence (pLDDT)

The mean pLDDT of this model is 92.9 (very high overall). pLDDT is AlphaFold's per-residue confidence score from 0 to 100. In MolViewer, choose the B-factor color scheme to color the model by pLDDT, because AlphaFold stores it in the B-factor column.

pLDDT band	Meaning	Share of residues
Above 90	Very high: backbone and side chains are usually accurate	76%
70 to 90	Confident: backbone generally right	22%
50 to 70	Low: treat with caution	2%
Below 50	Very low: often disordered regions	0%

What pLDDT means and how to read it

Function

One of the components of the core complex of photosystem II (PSII). PSII is a light-driven water:plastoquinone oxidoreductase that uses light energy to abstract electrons from H(2)O, generating O(2) and a proton gradient subsequently used for ATP formation. It consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. Required for association of PsbZ and Psb30/Ycf12 with PSII (PubMed:20194360)

Subunit structure

PSII is composed of 1 copy each of membrane proteins PsbA, PsbB, PsbC, PsbD, PsbE, PsbF, PsbH, PsbI, PsbJ, PsbK, PsbL, PsbM, PsbT, PsbX, PsbY, PsbZ, Psb30/Ycf12, peripheral proteins PsbO, CyanoQ(PsbQ), PsbU, PsbV and a large number of cofactors. It forms dimeric complexes. Part of a photosystem II (PSII) assembly intermediate complex PSII-I; crystallized from a strain deleted of psbJ, it forms…

Subcellular location

Cellular thylakoid membrane

Experimental structures in the PDB

Compare the prediction with experimentally determined structures of the same protein:

PDB ID	Method	Resolution	Chains and residues
9EVX	EM	1.71 Å	K/k=1-46
7RF1	X-ray	1.89 Å	K/k=1-46
7YQ2	X-ray	1.9 Å	K/k=1-46
7YQ7	X-ray	1.9 Å	K/k=1-46
8F4C	X-ray	2.0 Å	K/k=1-46
8F4I	X-ray	2.0 Å	K/k=1-46
8F4J	X-ray	2.0 Å	K/k=1-46
6W1T	X-ray	2.01 Å	K/k=1-46
7RF6	X-ray	2.01 Å	K/k=1-46
8F4F	X-ray	2.03 Å	K/k=1-46
8F4G	X-ray	2.03 Å	K/k=1-46
6DHP	X-ray	2.04 Å	K/k=10-46
6DHE	X-ray	2.05 Å	K/k=10-46
6DHO	X-ray	2.07 Å	K/k=10-46
6DHF	X-ray	2.08 Å	K/k=10-46
6W1O	X-ray	2.08 Å	K/k=1-46
7RF2	X-ray	2.08 Å	K/k=1-46
11YO	X-ray	2.09 Å	K/k=1-46
6W1U	X-ray	2.09 Å	K/k=1-46
6W1V	X-ray	2.09 Å	K/k=1-46

Showing 20 of 65 experimental structures (best resolution first).

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