Internal repeats sequence homology

This program is used to find regions of homology. It will find internal repeats or common sequences between two sequences by displaying the two sequences in the form of a matrix and marking any regions of identity. One sequence is written along the x axis... 

The sequence of riboflavin synthase of B. subtilis, the first that became available, was determined at the protein level by Edman sequencing and, independently, by DNA sequencing. "" In line with the hypothesis that the enzyme could provide a pseudo-C2-symmetric environment, it was gratifying to observe that the 215 amino acid peptide shows strong internal sequence homology specifically, 26 amino acids in the internal sequence repeat of the B. subtilis enzyme are identical and 23 are similar (Figure 12). "" ... 

An unexpectedly large number of the proteins in each class exhibit strong internal symmetry, whereby repeated structural elements are arranged in nearly symmetrical fashion, usually related by two-fold rotations such as observed in the subunit of dimeric E. coli cyti-dine deaminase (Betts et al, 1994). Despite the absence of obvious sequence homology between the two halves of the enzyme, they clearly share similar folding instructions. 

Repeated sequence of acid proteinases arranged in a possible internal homology... 

Of fundamental significance to understanding transferrin structure and function is the two-fold internal amino acid sequence repeat. In each protein, the N-terminal half of the polypeptide is homologous with the C-terminal half, with the level of identity between the two halves ranging from 26-28% in the insect proteins to —40% in higher transferrins and as high as 46% in melanotransferrin. This repeat is expressed... 

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