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Role of Arginine 717 in insulin receptor respective Arginine 704 in IGF-1 receptor for the interaction with ligands
Kertisová, Anna ; Selicharová, Irena (advisor) ; Ryšlavá, Helena (referee)
Insulin and insulin-like growth factor 1 (IGF-1) are peptide hormones that are important regulators of cellular metabolism, proliferation and apoptosis. Disruptions in signalling pathways may cause a whole range of diseases from diabetes mellitus type 1 and type 2 to cancer or neurodegenerative diseases. The cellular response to these hormones is mediated by insulin (IR) and IGF-1 receptors (IGF-1R) with a tyrosin-kinase activity. Receptors are created as hetero-tetramers of two extracellular α-subunits and two intracellular β-subunits. Studies of receptor structures try to elucidate the basic principles of the interaction of receptors with their ligands. However, the role of some amino-acid residues in binding remains unclear. It was suggested that the arginine 704 of IGF-1R may interact with Glu58 IGF-1. In comparison with IGF-1R, the equivalent arginine 717 IR was not associated with an important role in insulin binding in previous studies. This thesis is focused on clarifying the role of Arg704 IGF-1R and for comparison analogically on Arg717 IR isoform A (IR-A) in ligand binding to the receptors. Therefore, mutant variants of IGF-1R in positions His697 and Arg704 and variants IR-A in positions His710 and Arg717 were created. The role of histidines 697 IGF-1R and 710 IR was already elucidated...
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The preparation and characterisation of analogues of insulin and IGF-2 selective for both isoform of insulin receptor and IGF-1 receptor
Mlčochová, Květoslava ; Žáková, Lenka (advisor) ; Obšil, Tomáš (referee) ; Šulc, Miroslav (referee)
Insulin and insulin-like growth factor 1 (IGF-1) and 2 (IGF-2) are related protein hormones with different but overlapping biological functions. All the hormones interact with a receptor within the insulin-IGF system (insulin receptor A and B, IGF-1 receptor), however with different affinity. The different interaction with individual receptors is just one of the main tools for regulation of the system that is essential for the proper functioning of the organism. Although the residues directly interacting with receptors are mainly located in A and B domains, the C and D domains probably play a role in receptor specificity. Here, we firstly focused on the impact of D domains of IGF-1 and 2 (D1 and D2 domains) and C domain of IGF- 2 (C2 domain). To probe the impact of C and D domains, we prepared insulin analogues containing a part of or an entire domain following a pattern seen in IGFs. The receptor-binding affinities of these analogues and their receptor autophosphorylation potentials were characterised. Our results revealed that the initial part of D1 domain has a detrimental effect on IR affinity that is only slightly enhanced by the rest of the D1 domain. D2 domain has rather neutral effect on IR affinity. We further showed that the addition of amino acids derived from the C2 domain to the...
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The preparation and characterisation of analogues of insulin and IGF-2 selective for both isoform of insulin receptor and IGF-1 receptor
Mlčochová, Květoslava ; Žáková, Lenka (advisor) ; Obšil, Tomáš (referee) ; Šulc, Miroslav (referee)
Insulin and insulin-like growth factor 1 (IGF-1) and 2 (IGF-2) are related protein hormones with different but overlapping biological functions. All the hormones interact with a receptor within the insulin-IGF system (insulin receptor A and B, IGF-1 receptor), however with different affinity. The different interaction with individual receptors is just one of the main tools for regulation of the system that is essential for the proper functioning of the organism. Although the residues directly interacting with receptors are mainly located in A and B domains, the C and D domains probably play a role in receptor specificity. Here, we firstly focused on the impact of D domains of IGF-1 and 2 (D1 and D2 domains) and C domain of IGF- 2 (C2 domain). To probe the impact of C and D domains, we prepared insulin analogues containing a part of or an entire domain following a pattern seen in IGFs. The receptor-binding affinities of these analogues and their receptor autophosphorylation potentials were characterised. Our results revealed that the initial part of D1 domain has a detrimental effect on IR affinity that is only slightly enhanced by the rest of the D1 domain. D2 domain has rather neutral effect on IR affinity. We further showed that the addition of amino acids derived from the C2 domain to the...
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Interaction studies of insulin, IGF-1/2 and IGF-1 analogue with insulin and IGF-1 receptors
Chrudinová, Martina ; Ryšlavá, Helena (advisor) ; Liberda, Jiří (referee)
Insulin-like growth factors 1 and 2 (IGF-1/2) are single-chain peptides exerting homology (in both amino-acid sequence and tertiary structure) to insulin. The main function of these peptides is promoting celular growth, proliferation and differentiation. Both insulin and insulin-like growth factors mediate their function through membrane receptors - insulin receptor (isoforms A and B) and IGF-1 receptor. All these receptors are members of the tyrosinkinase family of receptors and they exert the same subunit and domain composition. The activation of insulin and IGF-1 receptors is tightly associated with activation of two intracellular signaling pathways. The PI3-K/Akt pathway is involved in the glucose transport to the cell, induction of proliferation or inhibition of apoptosis, while the Ras/MAPK pathway is involved mainly in the induction of cell growth and differentiation. Due to the structure similarity in both the ligands and receptors, every ligand can activate different receptors (with different potency) and the signaling pathways associated with these receptors. Thus, the functions of IGFs and insulin, the same as their receptors, are overlapping. The distinct function of the concrete ligand can be distinguished by the different tissue distribution of both isoforms of insulin receptor and...
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