The binding of HIV-1 Gag and Gag-related proteins to model membranes was examined using three experimental systems: (i) large unilamellar phospholipid vesicles (LUVs) and recombinant Gag purified from Escherichia coli; (ii) LUVs added to a mammalian cell extract in which Gag proteins were expressed by a coupled transcription/translation system; and (iii) inside-out plasma membrane vesicles purified from human red blood cells (RBC) and recombinant, purified Gag from E. coli. Several novel aspects of HIV-1 Gag membrane interactions were observed: (i) Gag proteins bound with high affinity to both model membranes with a negatively charged surface and to RBC membranes. (ii) Binding of the Gag precursor and mature Gag proteins exhibited different sensitivities to ionic strength indicating that the precursor directed membrane binding through interactions that were qualitatively and quantitatively distinct from those of any of its individual domains. Studies using energy transfer between tryptophan residues in the proteins and anthroyloxy-containing probes inserted in the LUVs indicated that the orientation of the precursor and of the mature proteins on the membrane surface were distinct; (iii) Gag oligomers appear to have facilitated high-affinity binding under high salt conditions, suggesting that protein-protein interactions led to formation of stronger electrostatic or new hydrophobic membrane binding determinants. Since binding studies with model membranes permit quantitative analysis, these experimental approaches may permit identification of interactions that drive Gag assembly on the membrane.

This paper aims at introducing benchmarking to management practitioners. Emphases have been placed on the classification of benchmarking and the benchmarking process model. The former will help in identifying the sources of best practices as a result of assisting in promoting management perspectives and facilitating the formation of various specific goals. The latter, on the other hand, systematically introduces all necessary components in a benchmarking project. Additionally, effort is put in to clarify the meaning of benchmarking by introducing three useful working definitions. Some materials of benchmarking, including its background and benefits, are also given. Finally, some hints are provided to organizations that want to conduct first-time benchmarking project.

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