insertions

An insertions directive is used to specify insertions of a single residue. The syntax for specifying an insertion is as follows:

<chain>,<resid>,<resname>

<chain> is the chain ID, <resid> is the residue number (including an optionally appended insertion code) immediately after which the inserted residue is to be placed, and <resname> is the one-letter amino acid sequence to insert. The inserted residue acquires the same integer residue number as the residue indicated and an incremented insertion code (usually A if the reference residue itself does not already have an insertion code). For example, A,12,A would insert an alanine at position 12A in chain A . You can use either 1-byte or 3-byte residue names. For example, both A,12,A and A,12,ALA would insert an alanine at position 12A in chain A.