Model of a variable light-chain (VL) domain from mouse that binds to hen egg-white lysozyme.

"An antibody (Ab), also known as an immunoglobulin (Ig), is a large Y-shaped protein produced by B cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses."
http://en.wikipedia.org/wiki/Antibody

Antibodies of various kinds contain repeats of the so-called immunoglobulin (IG) domain:
http://en.wikipedia.org/wiki/Immunoglobulin_domain

The Variable IG domains bind to the target antigen. The model is a cartoon representation of the a variable light-chain IG domain from mouse that binds to hen eggwhite lysozyme. Residues involved in antigen-binding are represented as spheres. Model based on PDB entry 1YQV:
http://www.rcsb.org/pdb/explore.do?structureId=1yqv

STL file created using VMD:
http://www.ks.uiuc.edu/Research/vmd/

Successfully printed by a Replicator 2 in PLA using MakerWare(TM) 2.2.2.89, standard resolution (3 shells, 25% infill), with raft and supports.