There was a very interesting paper in Science last week. It describes a process in a class of immune cell called CD8+ T-lymphocytes, in which two peptides are spliced together in the reverse order to that predicted from gene sequence. The reaction is believed to be a transpeptidation catalysed by the 20S proteasome and the process may be a way of generating additional antigen diversity.
New Scientist covered the story under the headline “Frankenstein protein defies biology textbooks”, telling us that “it has always been believed that the structure of a protein is fixed by the DNA template that encodes it”. I think this is a case of slight over-dramatisation and besides, is not really true. We’ve known about inteins, or “protein introns”, for many years now. It strikes me once again that many researchers and writers lack awareness of many biological processes because they continually neglect the Archaea.