Insulin: Difference between revisions
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Insulin acts antagonistically to the hormone [[Glucagon|glucagon]], which acts on [[Glycogen|glycogen]] storage in response to low blood sugar levels <ref>Berg J., Tymoczko J and Stryer L. (2007) Biochemistry, 6th edition, New York: WH Freeman.fckLR</ref>. This serves as an effective [[Homeostatis|homeostasis]] mechanism. <br> | Insulin acts antagonistically to the hormone [[Glucagon|glucagon]], which acts on [[Glycogen|glycogen]] storage in response to low blood sugar levels <ref>Berg J., Tymoczko J and Stryer L. (2007) Biochemistry, 6th edition, New York: WH Freeman.fckLR</ref>. This serves as an effective [[Homeostatis|homeostasis]] mechanism. <br> | ||
=== Forming the structure of Insulin === | === Forming the structure of Insulin === | ||
Insulin has two [[Proteins|peptide chains]], named a and b which are linked together by [[Cysteine|disulphide bonds]] between each of the two chains. Proinsulin is the molecule that insulin is synthesised from, unlike insulin it contains three peptide chains (a, b and c). Proinsulin folds to the correct shape through the formation of the disulphide bonds between the a and b peptide chains and then the peptide chain, c, located between the a and the b chains is removed in order to complete the structure of insulin. | Insulin has two [[Proteins|peptide chains]], named a and b which are linked together by [[Cysteine|disulphide bonds]] between each of the two chains. [[Proinsulin|Proinsulin]] is the molecule that insulin is synthesised from, unlike insulin it contains three peptide chains (a, b and c). Proinsulin folds to the correct shape through the formation of the [[Disulphide_bond|disulphide bonds]] between the a and b peptide chains and then the peptide chain, c, located between the a and the b chains is removed in order to complete the structure of insulin. | ||
=== References === | === References === | ||
<references /> | <references /> | ||
Revision as of 10:42, 12 November 2011
Insulin is a hormone. Its main function is the regulation of blood sugar levels, by causing the liver and muscles to increase uptake of glucose [1]. Insulin is produced from a single gene which codes for the peptide proinsulin; a precursor molecule. Mutations in this gene can result in a faulty protein; causing type 1 diabetes or a possible predisposition to type 2 diabetes [2][3].
Insulin regulates the blood glucose levels in different ways. It enhances the glucose transport at a cellular level by stimulation of the glucose transporter (GLUT) family.
Insulin also has an effect on gene expression which is up or down regulated in the homeostasis process to maintain the optimum blood glucose levels.
Insulin is released by the beta-cells of the pancreas.
Insulin stimulates glycogen synthesis
When blood sugar levels are high, insulin binds to a tyrosine kinase receptor. Binding of insulin triggers a phosphorylation cascade, preventing phosphorylation of glycogen synthase as this inactivates it's activity [4].
Insulin acts antagonistically to the hormone glucagon, which acts on glycogen storage in response to low blood sugar levels [5]. This serves as an effective homeostasis mechanism.
Forming the structure of Insulin
Insulin has two peptide chains, named a and b which are linked together by disulphide bonds between each of the two chains. Proinsulin is the molecule that insulin is synthesised from, unlike insulin it contains three peptide chains (a, b and c). Proinsulin folds to the correct shape through the formation of the disulphide bonds between the a and b peptide chains and then the peptide chain, c, located between the a and the b chains is removed in order to complete the structure of insulin.
References
- ↑ http://www.ncbi.nlm.nih.gov/omim/176730
- ↑ http://www.ncbi.nlm.nih.gov/omim/176730
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/20806184
- ↑ Berg J., Tymoczko J and Stryer L. (2007) Biochemistry, 6th edition, New York: WH Freeman.fckLR
- ↑ Berg J., Tymoczko J and Stryer L. (2007) Biochemistry, 6th edition, New York: WH Freeman.fckLR