Amino Acid SequenceAmino AcidsAmino Acid SubstitutionSelection, GeneticSequence Homology, Amino AcidMolecular Sequence DataMutationBase SequenceCloning, MolecularSequence AlignmentMutagenesis, Site-DirectedSequence Analysis, DNAPoint MutationPhylogenyEvolution, MolecularGenetic VariationMutation, MissenseModels, MolecularEscherichia coliBinding SitesCell LineStructure-Activity RelationshipSequence Homology, Nucleic AcidPhenotypeProtein Structure, TertiaryProtein ConformationSpecies SpecificityAmino Acids, EssentialCodonAmino Acid MotifsPolymerase Chain ReactionAllelesRecombinant ProteinsDNA, ComplementaryMutagenesisDNA PrimersDNA Mutational AnalysisAmino Acid Transport SystemsKineticsBacterial ProteinsDNAProtein BindingBiological EvolutionGenes, BacterialConserved SequencePolymorphism, GeneticRestriction MappingPeptide FragmentsRecombinant Fusion ProteinsViral ProteinsPlasmidsSubstrate SpecificityVirulenceLeucinePeptidesViral Envelope ProteinsModels, GeneticVirus ReplicationGenes, ViralHemagglutinin Glycoproteins, Influenza VirusProtein Structure, SecondarySaccharomyces cerevisiaeProteinsGenotypeSerial PassageRNA, MessengerGenesExonsCapsid ProteinsEpitopesCarrier ProteinsAdaptation, BiologicalAmino Acids, AromaticIsoleucineAlanineAmino Acids, Branched-ChainHIV-1RNA, ViralOpen Reading FramesAmino Acids, SulfurMolecular WeightTransfectionAntigenic VariationGenome, ViralSequence AnalysisSequence DeletionGene LibraryTranscription, GeneticCapsidDNA, ViralElectrophoresis, Polyacrylamide GelCattleCricetinaeGlycineChickensHIV Envelope Protein gp120Genetic Complementation TestDirected Molecular EvolutionDNA, BacterialMembrane Proteins