Home Research -G.Ames Lab -Introduction -Symposium Presentation -My Work End Index -Introduction -Histidine Permease -Transport Cycle -HisJ Structure -HisQ and HisM Topology

The difficulty with crystallizing transmembrane proteins is that they have many hydrophobic regions which span the membrane.  The hydrophobic regions cause these transmembrane proteins to aggregate and precipatate out of solution.  As a result, these proteins just don't grow crystals.  It's clear that some detergents are necessary in order to facilitate crystallization, but no one has figured out this problem yet.  I'm not a crystallographer so I can't get into too much detail about all of this.  Even though we can't crystallize the HisQ and HisM subunits, we have a proposed topology based on the amino acid sequence as well as fragments obtained from proteolytic digestions.  It is important to note that HisQ and HisM share a similar topology, but they have vastly different properties.  For example, HisM is very heat-senstive while HisQ is more stable.  The main focus of my work now is to study the nature of the interaction between HisJ and HisQ.