3QJO: Refined Structure of the functional unit (KLH1-H) of keyhole limpet hemocyanin

Hemocyanins are multimeric oxygen-transport proteins in the hemolymph of many arthropods and mollusks. The overall molecular architecture of arthropod and molluscan hemocyanin is very different, although they possess a similar binuclear type 3 copper center to bind oxygen in a side-on conformation. Gastropod hemocyanin is a 35 nm cylindrical didecamer (2 x 10-mer) based on a 400 kDa subunit. The latter is subdivided into eight paralogous "functional units" (FU-a to FU-h), each with an active site. FU-a to FU-f contribute to the cylinder wall, whereas FU-g and FU-h form the internal collar complex. Atomic structures of FU-e and FU-g, and a 9 A cryoEM structure of the 8 MDa didecamer are available. Recently, the structure of keyhole limpet hemocyanin FU-h (KLH1-h) was presented as a C(alpha) -trace at 4 A resolution. Unlike the other seven FU types, FU-h contains an additional C-terminal domain with a cupredoxin-like fold. Because of the resolution limit of 4 A, in some loops, the course of the protein backbone could not be established with high certainty yet. Here, we present a refined atomic structure of FU-h (KLH1-h) obtained from low-resolution refinement, which unambiguously establishes the course of the polypeptide backbone and reveals the disulfide bridges as well as the orientation of bulky amino acids.
PDB ID: 3QJODownload
MMDB ID: 90832
PDB Deposition Date: 2011/1/30
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 4  Å
Source Organism:
Similar Structures:
Biological Unit for 3QJO: dimeric; determined by author and by software (PISA)
Molecular Components in 3QJO
Label Count Molecule
Proteins (2 molecules)
Hemocyanin 1
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

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