Unusual sequence numbering: Difference between revisions

Sometimes the initial sequence number is zero.

Sometimes the initial sequence number is negative. This is usually done when residues were engineered onto the N-terminus. The transition from -1 to 1 may or may not include a residue numbered zero. An example is [http://firstglance.jmol.org/fgij/fg.htm?1d5t 1d5t] ([[1d5t]]). The N-terminal Met of the [http://www.uniprot.org/uniprot/P21856#sequences genomic sequence] is numbered 1. But a di-histidine tag was engineered onto the N-terminus: His -2, His -1, Met 1. In this case, there is no residue numbered zero. The C-terminal residue is Phe431, but the length of the genomic sequence is 447. The C-terminal 16 residues of the genomic sequence were not present in the crystallized protein. In this model, no residues are missing due to crystallographic disorder.