Cystatin B gene has a particular repeating sequence of 12 DNA nucleotides known as dodecamer repeat which is repeated two or three times in the gene that helps Cystatin B protein production. It is mapped in cytogenetic location 21q22.3 and in molecular location on chromosome 21 with base pairs 43,773,664 to 43,776,374.
Cystatin B lessens the activity of enzyme cathepsins that aid in breaking down proteins in lysosomes. It is widely found and isolated from the humanspleen and liver where its amino sequence has been fully determined and found intracellularly and extracellularly that form dimer in stabilized noncovalent forces.
Cystatin B gene mutations caused Unverricht-Lundborg disease due to an increased number of copies on the dodecamer repeat which usually has more than 30 repeats in two copies wherein one copy has the expanded dodecamer repeat while the second copy carries one of the nine other identified mutations that substitute one amino acids with another amino acids resulted in an improper functions of proteins or incorrectly pieced together.
Gene name: CSTB
Protein name: Cystatin-B