RT Journal
A1 Fassler, Jan
A1 Landsman, David
A1 Acharya, Asha
A1 Moll, Jonathan R.
A1 Bonovich, Maria
A1 Vinson, Charles
T1 B-ZIP Proteins Encoded by the Drosophila Genome: Evaluation of Potential Dimerization Partners
JF Genome Research 
JO Genome Research 
YR 2002 
FD August 01 
VO 12 
IS 8 
SP 1190 
OP 1200 
DO 10.1101/gr.67902 
UL http://genome.cshlp.org/content/12/8/1190.abstract 
AB The basic region-leucine zipper (B-ZIP) (bZIP) protein motif dimerizes to bind specific DNA sequences. We have identified 27 B-ZIP proteins in the recently sequenced Drosophila melanogaster genome. The dimerization specificity of these 27 B-ZIP proteins was evaluated using two structural criteria: (1) the presence of attractive or repulsive interhelical g↔e‘ electrostatic interactions and (2) the presence of polar or charged amino acids in the ‘a’ and ‘d’ positions of the hydrophobic interface. None of the B-ZIP proteins contain only aliphatic amino acids in the‘a’ and ‘d’ position. Only six of theDrosophila B-ZIP proteins contain a “canonical” hydrophobic interface like the yeast GCN4, and the mammalian JUN, ATF2, CREB, C/EBP, and PAR leucine zippers, characterized by asparagine in the second ‘a’ position. Twelve leucine zippers contain polar amino acids in the first, third, and fourth ‘a’ positions. Circular dichroism spectroscopy, used to monitor thermal denaturations of a heterodimerizing leucine zipper system containing either valine (V) or asparagine (N) in the ‘a’ position, indicates that the V–N interaction is 2.3 kcal/mole less stable than an N–N interaction and 5.3 kcal/mole less stable than a V–V interaction. Thus, we propose that the presence of polar amino acids in novel positions of the ‘a’ position of Drosophila B-ZIP proteins has led to leucine zippers that homodimerize rather than heterodimerize.