Truncated hemoglobin (IPR001486)

Short name: Hemoglobin_trunc

Overlapping homologous superfamilies

Family relationships


This entry represents a group of haemoglobin-like proteins found in eubacteria, cyanobacteria, protozoa, algae and plants, but not in animals or yeast. These proteins have a truncated 2-over-2 rather than the canonical 3-over-3 alpha-helical sandwich fold [PMID: 15598493]. They include:

  • HbN (or GlbN): a truncated haemoglobin-like protein that binds oxygen cooperatively with a very high affinity and a slow dissociation rate, which may exclude it from oxygen transport. It appears to be involved in bacterial nitric oxide detoxification and in nitrosative stress [PMID: 16814781].
  • Cyanoglobin (or GlbN): a truncated haemoprotein found in cyanobacteria that has high oxygen affinity, and which appears to serve as part of a terminal oxidase, rather than as a respiratory pigment [PMID: 10684619].
  • HbO (or GlbO): a truncated haemoglobin-like protein with a lower oxygen affinity than HbN. HbO associates with the bacterial cell membrane, where it significantly increases oxygen uptake over membranes lacking this protein. HbO appears to interact with a terminal oxidase, and could participate in an oxygen/electron-transfer process that facilitates oxygen transfer during aerobic metabolism [PMID: 11796724].
  • Glb3: a nuclear-encoded truncated haemoglobin from plants that appears more closely related to HbO than HbN. Glb3 from Arabidopsis thaliana (Mouse-ear cress) exhibits an unusual concentration-independent binding of oxygen and carbon dioxide [PMID: 11526234].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0019825 oxygen binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.