atom_selection with segid?

[Ash]

Hi, I am working with a homo-dimeric complex of two protein trajectories (dcd). (Protein 1= chain A & B, a homodimer, Protein 2= chain C & D, a homodimer). My PDB file contains chain name of X for the whole complex but different segid's "PROA, PROB, PROC and PROD. Like every homodimer, resids are similar for every segid. I want to use atom.select() with segid instead of chain id but there are no information in index section. I tried different things but failed. Please see the pdb file in attachment.

ATOM 4 HT3 SER X 2 -2.465 13.784 -1.157 1.00 0.00 PROA

ATOM 1004 HD1 ARG X 19 -3.653 9.263 -11.152 1.00 0.00 PROB

[Barry Grant]

Will something like this not work for you:

library(bio3d)
pdb <- read.pdb("~/Downloads/123.pdb")

# example: select residue number 3 from segid PROA
atom.select(pdb, resno=3, segid = "PROA", value = TRUE)$atom