Amino acids are the building blocks of proteins. Put very simplistically, our genes tell our bodies which amino acids to put into the proteins that we make, and it is the proteins that make up the significant constituents of our bodies. Myelin Basic Protein (MBP) is an example of one such protein.
In order to understand how amino acids are glued together to make proteins, we must look at the DNA (deoxyribonucleic acid) that is present in almost all the cells in our bodies.
DNA is built up of very many sub-units called neucleotides, each of which contains a chemical "base". There are only four different bases and thus only four different nucleotides. The four bases are adenine (A), thymine (T), cytosine (C) and guanine (G).
Genes are sections of DNA, in which the neucleotides are viewed in groups of three called "triplets" or "codons". Each codon "codes" for a particular amino acid. A gene is terminated by a stop code or terminator which is represented by one of three codons that do not code for amino acids.
There are 20 different amino acids that are used in animals (there are others that are used in plants). There are 64 different codons and most of the 20 amino acids are coded for by more than one triplet (see table below).
The process of synthesing amino acids from genes is known as transcription. During transcription, a gene is echoed from the DNA into a complementary form called ribonucleic acid (RNA).
From the RNA, amino acids are produced and are joined
with one another with a peptide bond. The resulting
sequence of amino acids is known as peptide string or polypeptide. Proteins
are derived from these polypeptides.
|Abbreviation||Amino acid name||Neucleotide sequences (codons)|
|Ala||Alanine||GCT, GCC, GCA, GCG|
|Arg||Arginine||CGT, CGC, CGA, CGG, AGA, AGG|
|Asp||Aspartic Acid||GAT, GAC|
|Glu||Glutamic Acid||GAA, GAG|
|Gly||Glycine||GGT, GGC, GGA, GGG|
|Ile||Isoleucine||ATT, ATC, ATA|
|Leu||Leucine||TTG, TTA, CTT, CTC, CTA, CTG|
|Pro||Proline||CCT, CCC, CCA, CCG|
|Ser||Serine||TCT, TCC, TCA, TCG, AGT, AGC|
|Thr||Threonine||ACT, ACC, ACA, ACG|
|Val||Valine||GTT, GTC, GTA, GTG|
|End||Terminator||TAA, TAG, TGA|
You will sometimes see these abbreviations:
Asx Aspartic Acid or Asparagine GAT,GAC,AAT,AAC
Glx Glutamic Acid or Glutamine GAA,GAG,CAA,CAG
Xxx or Xaa Unknown
where the derivation is uncertain or unknown.
Amino Acid links:
Encyclopedia Entry - amino acid
Encyclopedia Entry - peptide
Encyclopedia Entry - protein
Encyclopedia Entry - nucleic acid
Incomplete nucleic acid sequences
Symbols Used for Nucleotide and Amino Acid Sequence Data