Evolution of thyroid hormone distributor proteins. (25th December 2017)

• Record Type: Journal Article
• Authors: McLean, Thomas R.; Rank, Michelle M.; Smooker, Peter M.; Richardson, Samantha J.
• Is Part Of: Molecular and cellular endocrinology. Volume 459(2017)
• Page Start: 43
• Page End: 52
• Publication Date: 2017-12-25
• Subjects: Albumin -- Positive selection -- Protein evolution -- Thyroid hormone -- Thyroxine-binding globulin -- Transthyretin; Endocrinology -- Periodicals; Molecular biology -- Periodicals; Cytology -- Periodicals; Endocrinology -- Periodicals; Hormones -- Periodicals; Endocrinologie -- Périodiques; Cytology; Endocrinology; Molecular biology; Periodicals; 573.4
• DOI: 10.1016/j.mce.2017.02.038
• Languages: English
• ISSNs: 0303-7207

Abstract

Abstract: Thyroid hormones (THs) are evolutionarily old hormones, having effects on metabolism in bacteria, invertebrates and vertebrates. THs bind specific distributor proteins (THDPs) to ensure their efficient distribution through the blood and cerebrospinal fluid in vertebrates. Albumin is a THDP in the blood of all studied species of vertebrates, so may be the original vertebrate THDP. However, albumin has weak affinity for THs. Transthyretin (TTR) has been identified in the blood across different lineages in adults vs juveniles. TTR has intermediate affinity for THs. Thyroxine-binding globulin has only been identified in mammals and has high affinity for THs. Of these THDPs, TTR is the only one known to be synthesised in the brain and is involved in moving THs from the blood into the cerebrospinal fluid. We analysed the rates of evolution of these three THDPs: TTR has been most highly conserved and albumin has had the highest rate of divergence. Graphical abstract: Highlights: Of the 3 TH distributor proteins, albumin evolved fastest and TTR evolved slowest. TH binding sites in TTR and TBG were highly conserved, those in albumin were not. Amino acids possibly undergoing positive selection were away from TH binding sites in each protein.