(a) What are low complexity regions and how are they handled in database searching and why?
(b) What is the importance of E-value in database searching?
a) Low complexity regions(LCRs) are amino acid sequences that contain repeats of single amino acids or short amino acid motifs. An algorithm for detecting and masking LCRs in protein sequences improve the quality of database searches. The algorithm is based on the complexity analysis of subsequences delimited by a pair of identical, repeating subsequences.
b) The Expect value (E) is a parameter that describes the number of hits one can expect to see by chance when searching a database of a particular size.