|Protein Name||Inter-alpha-trypsin inhibitor heavy chain H1|
|Ref Sequence ID||XP_005222812.1|
|Protein Existence Status||Unreviewed: Experimental evidence at protein level|
|Presence in other biological fluids/tissue/cells||IαI family proteins are mainly secreted by the liver and present in the blood;|
|Protein Function||plasma serine-proteinase inhibitor; ITIH4 is a liver-derived member of the ITI family with diverse functions as an anti-apoptotic and matrix- stabilizing molecule that is important throughout development; ITIH4 is a significant biomarker to assess particulate matter in patients with chronic obstructive pulmonary disease|
|Biochemical Properties||The 3 isoforms are all expressed in the liver and coupled with bikunin before they are released into blood circulation - difference being their selective combination with bikunin; The heavy chain(HC)1–3 prepropeptides (∼900 amino acid residues) comprise a signal peptide, a short propeptide, a mature form of HC, and a C-terminal polypeptide; hyaluronan is the most recognized HC interacting molecule; HCs are observed to be covalently linked to hyaluronan via a transesterification reaction, where they are often referred to as SHAP (serum-derived hyaluronanassociated proteins; The effects of SHAPs on hyaluronan include protection against free radicals, enhancement of macromolecular aggregation, and an increase in the binding avidity to other matrix components;|
|Significance in milk||acute phase protein in cattle- was isolated from heifers with experimentally induced 'summer mastitis'|
|PTMs||Glycosylated: two potential N-glycosylation sites of H1 are effectively fully occupied by complex-type N-glycans- predominantly of biantennary type; H2 heavy chain carries only one complex-type N-glycan attached to Asn64; O-glycan carried by Thr637, two or three additional O-linked carbohydrate chains are present on H2-consist of a type-1 core structure with one or two NeuAc moieties;|
|Significance of PTMs||O glycans influences the metabolism of IaI- preferentially cleaves the H2 heavy chain in its Cterminal part which is enhanced by charge-mediated interactions between the glycosaminoglycan chain of IaI and elastase- mediated byO-glycan chains located in the C-terminal part of H2|
|Bibliography||1. Flahaut, C., Capon, C., Balduyck, M., Ricart, G., Sautiere, P., & Mizon, J. (1998). Glycosylation pattern of human inter-alpha-inhibitor heavy chains. The Biochemical Journal, 333 ( Pt 3), 749–756. https://doi.org/10.1042/bj3330749. |
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