1CQ4: Protein

CI2 mutant with tetraglutamine (mgqqqqgm) replacing MET59. Determined by X-ray diffraction at 1.8 Å resolution. Released 25 Nov 1998.

Method: X-ray diffraction
Resolution: 1.8 Å
Organism: Hordeum vulgare
Chains: 2
Atoms: 541
Mol. weight: 8.19 kDa
Released: 25 Nov 1998

Explore 1CQ4 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

1CQ4 contains 2 α-helices and 7 β-strands across 2 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 2 helices, 3 β-strands

Element	Residues	Length	Sheet
β-strand	23	1	1
α-helix	25-27	3
β-strand	31	1	2
α-helix	32-42	11
β-strand	47-52	6	1

Chain B: 0 helices, 4 β-strands

Element	Residues	Length	Sheet
β-strand	65-70	6	1
β-strand	75	1	2
β-strand	76	1	1
β-strand	81-82	2	1

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Protein (serine proteinase inhibitor 2)	A	protein	47	Hordeum vulgare	P01053 (AlphaFold model)
Protein (serine proteinase inhibitor 2)	B	protein	24	Hordeum vulgare	P01053 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>1CQ4_1 PROTEIN (SERINE PROTEINASE INHIBITOR 2) (chains A)
MKTEWPELVGKSVEEAKKVILQDKPEAQIIVLPVGTIVTMGQQQQGM

Sequence of entity 2 (B), FASTA

>1CQ4_2 PROTEIN (SERINE PROTEINASE INHIBITOR 2) (chains B)
EYRIDRVRLFVDKLDNIAQVPRVG

Primary citation

Crystal structure of a dimeric chymotrypsin inhibitor 2 mutant containing an inserted glutamine repeat. Chen, Y.W., Stott, K., Perutz, M.F. Proc Natl Acad Sci U S A (1999) 96:1257-1261. DOI 10.1073/pnas.96.4.1257 · PubMed

Other PDB entries of the same protein (UniProt P01053 (AlphaFold model), which also has an AlphaFold model), best resolution first:

7A3M 1.01 Å, Synergistic stabilization of a double mutant in CI2 from an in-cell library screen
7AON 1.3 Å, Crystal structure of CI2 double mutant L49I,I57V
1LW6 1.5 Å, Crystal Structure of the Complex of Subtilisin BPN' with Chymotrypsin Inhibitor 2 at 1.5…
6QIY 1.5 Å, CI-2, conformation 1
6QIZ 1.65 Å, CI-2, conformation 2
1YPC 1.7 Å, Direct observation of better hydration at the N-terminus of an alpha-helix with glycine…
5FFN 1.8 Å, Complex of subtilase SubTY from Bacillus sp. TY145 with chymotrypsin inhibitor CI2A
7AOK 1.87 Å, Crystal structure of CI2 mutant L49I
5FBZ 1.9 Å, Structure of subtilase SubHal from Bacillus halmapalus - complex with chymotrypsin…
7A1H 1.9 Å, Crystal structure of wild-type CI2
1YPA 2.0 Å, Direct observation of better hydration at the N-terminus of an alpha-helix with glycine…
1YPB 2.0 Å, Direct observation of better hydration at the N-terminus of an alpha-helix with glycine…

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