Doubt for PDB and chains

[bio_informatics]

Hello Members,
I am working on PDB files, extracting sequences, visualize them in tools, align using PDB files.

I have few doubts on PDB:
- Sometimes PDB file contains multiple chains.
Why there are multiple chains? Do all chains combine and give the resultant protein? Or each individual chain represents the same protein.

- I get ligand information in PDB, and if I have multiple chains. To which does it bind?
Does it bind to all chains?

Thanks in advance.

[bio_informatics]

*bounce*. Please help members.

[GenoMax]

This page should help: http://www.rcsb.org/pdb/101/static10..._tutorial.html

[bio_informatics]

That helps and clears many clouds.
Thank you GenoMax.