Unusual sequence numbering: Difference between revisions
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===Starts With Zero Or Negative Numbers=== | ===Starts With Zero Or Negative Numbers=== | ||
'''Zero.''' Sometimes the initial sequence number is zero. | '''Zero.''' Sometimes the initial sequence number is zero. An example is [http://firstglance.jmol.org/fgij/fg.htm?1bxw 1bxw] ([[1bxw]]). The first 21 residues of the [genomic sequence] are a signal sequence. The crystallized protein was engineered to start at residue 22 of the genomic sequence, which is Ala1 of the mature protein. A Met was engineered onto the N-terminus presumably to assist with expression. It was numbered Met0. (The crystallized protein ends at 178, but the length of the genomic sequence of the mature protein is 346 - 21 = 325. | ||
'''Negative.''' 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. | '''Negative.''' 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. | ||
