Translational units/Overview

Translational units begin with the RBS, the site of translational initiation, and end with a stop codon, the site of translational termination. Every translational unit in the Registry consists of at least three protein domains, a Head Domain, one or more Internal Domains including Special Internal Domains, and a Tail Domain. Thus translational units can, in some sense, be thought of as a composite part made up of three or more protein domains. Protein coding sequences, in contrast, begin with a start codon and end with a stop codon.

For more information on protein domains, see protein domains. Unfortunately, the original BioBrick assembly standard, Assembly standard 10, does not support in-frame assembly of protein domains. (Assembly standard 10 creates an 8 bp scar between adjacent parts.) Therefore, it is recommended that you use an alternate approach to assemble protein domains together to make a translational unit. There are several possible approaches to assembling protein domains including direct synthesis (preferred because it creates no scars) as well as various assembly standards. Regardless of which standard you choose, we suggest that the resulting translational unit comply with the original BioBrick assembly standard so that your parts can be assembled with most of the parts in the Registry.

Translational units should be as follows

GAATTC GCGGCCGC T TCTAGA G [RBS] [ATG ... TAA TAA] T ACTAGT A GCGGCCG CTGCAG

Although most RBSs are currently specified as separate parts in the Registry, we are now moving to a new design in which the RBS is included within the Head domain as a single part. The new design has the advantage of encapsulating both ribosome binding and translational initiation within a single part. Our working hypothesis is that the new design will reduce the likelihood of unexpected functional composition problems between the RBS and coding sequence.