Gene expression and function in biological systems

Gene is hereditary material made of the genetic material, the DNA. The DNA contains coding sequence that codes for proteins. These proteins, their structure, and amino acid sequences all depend on the genetic sequence on the coding sequence. Functions of the proteins are more dependent on the structure of the protein. Some of the main functions of the proteins include secretions, structural functions as keratin of hair and collagen of hair, and nails and transportation functions as proteins embedded in the cell membrane.

APO Milano-1 gene

APO Milano-1 gene is the mutant form of ApoA1. The protein produced from ApoA1 functions in clearing out cholesterol from the arteries. Apolipoproteins are an important of the HDL. HDL or the high-density lipoproteins are particles that are responsible for carrying cholesterol from the tissues towards the liver. HDL contain 50% lipid including phospholipids, triglycerides, and cholesterol and 50% Apolipoproteins that include ApoA-I and ApoA-II (Futterman, and Lemberg 244). One of the main constituents of the plasma HDL is ApoA-I. Cholesterol is steroid-based fat produced in the liver and intestines. The main function of the cholesterol is the production of hormones, bile acids, and steroid hormones sand for the maintenance of fluidity of the cell membranes. One of the main facts that need to be highlighted here is that higher the level of LDL (low density lipoproteins) as well as triglycerides, greater is the risk of cardiovascular infarctions. Risks of cardiovascular infarctions are inversely related to the presence of HDL, higher the levels of HDL, lesser is the risk of cardiovascular infarctions. Second important function of the HDL is protection against cardiovascular malfunctions. APO Milano-1 is a naturally occurring mutation first reported in the 18th century by Dr. Cesare Sirtori in Milan, Italy. It has been the first reported abnormality of the apolipoproteins. Reports and studies have highlighted that the carriers of the gene have lower levels of cholesterol and are seen to have lesser risks of heart malfunctions (Nissen et al. 2293).

APO Milano-1 Gene at the Molecular Level

The gene ApoA1 is located on chromosome 11, long arm (q), bands 23 and 24, abbreviated as 11q23-24. At the molecular level, the mutation in the normal ApoA1 is because of a single amino acid substitution at the position 173, cysteine amino acid substitutes or replaces the arginine amino acid. Because of the presence of an extra cysteine, a cysteine bridge is formed that causes great changes in the protein structure. ApoA1 protein does not have a cysteine dimer but cysteine dimer is formed on Apo1 Milano that causes the protein to exist as a homo or a hetro dimer with ApoAII (Futterman and Lemberg 246). It has been reported that he enhanced cholesterol removal efficiency is not because of the presence of extra cysteine. Based on the replacement of arginine by a cysteine residue, the charge of the protein is shifter towards cathode. Because of the mutation, it has been reported that the removal of cholesterol from the inner arterial walls is accelerated and much higher. The placebo trails and the clinical trials have shown that as compared to ApoA1, Apo Milano-1 can additionally clear up to 30% of atheroma from the arterial walls. The clinical trials have also shown that the plaques build inside the arterial walls are greatly reduced by Apo Milano-1 (Nissen et al. 2296).