MIT conducted an in-depth study of duplicate protein sequences

About 70 percent of human proteins contain at least one sequence consisting of a single amino acid that is repeated many times, interspersed with some other amino acids

Using their technique, the researchers analyzed all the proteins

Byron Lee, a graduate student at MIT, said: "We didn't study specific LCRs and their functions because they are involved in different processes, so they appear to be separate, and our broader approach allows us to see similarities between their properties, suggesting that the function of

Large-scale research

Previous studies have shown that LCRs are involved in a variety of cellular processes, including cell adhesion and DNA binding

"What we want to do is take a step back, instead of looking at individual LCRs, try to look at all the LCs and see if we can observe some patterns on a larger scale, which may help us figure out what the LCRs with the specified function are doing, and it also helps us understand what some LCRs that don't have a specified function are doing

To do this, the researchers used a technique called dot matrix, a method of visually representing amino acid sequences that can generate images

As a demonstration, the researchers picked out a human protein called RPA43, which has three lysine-rich LCRs

Biological components

In comparing proteins found in 8 different species, the researchers found that some LCRs types are highly conserved between species, meaning that sequences change little on evolutionary

"These sequences seem to be important for the assembly of certain parts of the nucleoli," Lee said

The researchers also found differences

Another structure that appears to have many conserved LCRs is the nucleus plaque, which is found

The team also found some examples of structures with LCRs that appear to diverge

The researchers now plan to extend their LCRs analysis to other species