Globin/Protoglobin
IPR012292
Definition
Globins are haem-containing proteins involved in binding and/or transporting oxygen. They belong to a very large and well studied family that is widely distributed in many organisms PMID:17540514. Globins have evolved from a common ancestor and can be divided into three groups: single-domain globins, and two types of chimeric globins, flavohaemoglobins and globin-coupled sensors. Bacteria have all three types of globins, while archaea lack flavohaemoglobins, and eukaryotes lack globin-coupled sensors PMID:16600051. Several functionally different haemoglobins can coexist in the same species. The major types of globins include: Haemoglobin (Hb): tetramer of two alpha and two beta chains, although embryonic and foetal forms can substitute the alpha or beta chain for ones with higher oxygen affinity, such as gamma, delta, epsilon or zeta chains. Hb transports oxygen from lungs to other tissues in vertebrates PMID:16888280. Hb proteins are also present in unicellular organisms where they act as enzymes or sensors PMID:15598493. Myoglobin (Mb): monomeric protein responsible for oxygen storage in vertebrate muscle PMID:15339940. Neuroglobin: a myoglobin-like haemprotein expressed in vertebrate brain and retina, where it is involved in neuroprotection from damage due to hypoxia or ischemia PMID:12962627. Neuroglobin belongs to a branch of the globin family that diverged early in evolution. Cytoglobin: an oxygen sensor expressed in multiple tissues. Related to neuroglobin PMID:15804833. Erythrocruorin: highly cooperative extracellular respiratory proteins found in annelids and arthropods that are assembled from as many as 180 subunit into hexagonal bilayers PMID:17084861. Leghaemoglobin (legHb or symbiotic Hb): occurs in the root nodules of leguminous plants, where it facilitates the diffusion of oxygen to symbiotic bacteriods in order to promote nitrogen fixation. Non-symbiotic haemoglobin (NsHb): occurs in non-leguminous plants, and can be over-expressed in stressed plants PMID:17540516. Flavohaemoglobins (FHb): chimeric, with an N-terminal globin domain and a C-terminal ferredoxin reductase-like NAD/FAD-binding domain. FHb provides protection against nitric oxide via its C-terminal domain, which transfers electrons to haem in the globin PMID:11092893. Globin-coupled sensors: chimeric, with an N-terminal myoglobin-like domain and a C-terminal domain that resembles the cytoplasmic signalling domain of bacterial chemoreceptors. They bind oxygen, and act to initiate an aerotactic response or regulate gene expression [[cite:PMID:11481493], [cite:PMID:15598488]]. Protoglobin: a single domain globin found in archaea that is related to the N-terminal domain of globin-coupled sensors PMID:15096613. Truncated 2/2 globin: lack the first helix, giving them a 2-over-2 instead of the canonical 3-over-3 α-helical sandwich fold. Can be divided into three main groups (I, II and II) based on structural features PMID:17701548. Anaerobic nitrite reductase: phytoglobin that reduces nitrite to nitric oxide (NO) under anoxic conditions PMID:21495624. This domain superfamily is found in the entire globin family of proteins, including the microbial globins PMID:14560666.
12 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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