Lac Repressor

1996, 17 1/2" x 23 1/2"

In this acrylic painting of the lac repressor, Geis characterizes this tetramer representation as "four angry reindeer." Geis' painting depicts the lac repressor with both the tetramerization domain (on the bottom) and the headpieces ("antlers" of the "reindeer"). A complete crystal structure of this tetramer has not actually been determined yet.

Used with permission from the Howard Hughes Medical Institute ( All rights reserved.

Non-commercial Reprint Request

Related PDB Entry: 1TLF

Experimental Structure Citation

Friedman, A. M., Fischmann, T. O., & Steitz, T. A. (1995). Crystal structure of lac repressor core tetramer and its implications for DNA looping. Science, 268, 1721-1727.

About Lac Repressor

Molecule of the Month: Lac Repressor

The lac repressor is a protein that can bind to certain DNA sites to prevent binding of RNA polymerase. This can therefore prevent transcription of genes for lactose metabolism, until further action from other proteins. The tetramer structure forms a V-shape, with the headpieces attaching to DNA and possibly twisting the DNA into a loop.

Text References

Goodsell, D. (2003). Molecule of the Month: Lac Repressor. DOI: 10.2210/rcsb_pdb/mom_2003_3