Pretty cool piece of news.. kind of pushes the envelope of our grasp of living 
systems. It adds yet one more layer (upon layers) to the decisional machinery 
of cellular scale life.  It is a pure protein executed process, occurring 
within a ribosome… no RNA/DNA instructions involved!

>From Ray Kurzweil’s newsletter 
><http://www.kurzweilai.net/protein-partially-assembles-another-protein-without-genetic-instructions?utm_source=KurzweilAI+Daily+Newsletter&utm_campaign=954bfc4219-UA-946742-1&utm_medium=email&utm_term=0_6de721fb33-954bfc4219-281942553>
> :

 

Defying textbook science, amino acids (the building blocks of a protein) can be 
assembled by another protein and without genetic instructions, according to a 
study published today (Jan. 2) in Science.

It happens just before an incomplete protein is recycled due to an assembly 
failure: a protein called Rqc2 prompts ribosomes (which assemble proteins) to 
add just two amino acids (of 20 total) — alanine and threonine — over and over, 
and in any order, playing a role similar to that of messenger RNA.

The apparently random sequence of amino acids probably doesn’t work normally, 
but may serve specific purposes, the scientists suggest. The code could signal 
that the partial protein must be destroyed, or it could be part of a test to 
see whether the ribosome is working properly.

Evidence suggests that either or both of these processes could be faulty in 
neurodegenerative diseases such as Alzheimer’s, Amyotrophic lateral sclerosis 
(ALS), or Huntington’s.

The senior authors are Peter Shen, Ph.D., a postdoctoral fellow in biochemistry 
at the University of Utah; Adam Frost, M.D., Ph.D., assistant professor at 
University of California, San Francisco; Jonathan Weissman, Ph.D., a Howard 
Hughes Medical Institute investigator at UCSF; and Onn Brandman, Ph.D., at 
Stanford University.

The research was supported by grants from the Searle Scholars program, the 
National Institutes of Health, the Howard Hughes Medical Institute, Stanford 
University, and the University of Utah.

 

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