LacIplugin-autotooltip__default plugin-autotooltip_bigLacI: the protein encoded by the $lacI$ gene; also called the Lac repressor protein. Binds to lactose or IPTG; upon binding, it loses the ability to bind to $lacO$.: the proteinplugin-autotooltip__default plugin-autotooltip_bigProtein: a molecule that is formed by the translation of messenger RNAs (mRNAs). Functions that proteins provide are what usually give organisms their phenotypes. encoded by the $lacI$ geneplugin-autotooltip__default plugin-autotooltip_bigGene: read Chapters 02, 03, 04, 05, and 06 for a definition of gene :-); also called the Lac repressor proteinplugin-autotooltip__default plugin-autotooltip_bigLacI: the protein encoded by the $lacI$ gene; also called the Lac repressor protein. Binds to lactose or IPTG; upon binding, it loses the ability to bind to $lacO$.. Binds to lactose or IPTGplugin-autotooltip__default plugin-autotooltip_bigIPTG: isopropyl β-D-1-thiogalactopyranoside, an inducer of the Lac operon. IPTG binds to the Lac repressor protein (also known as LacI).; upon binding, it loses the ability to bind to $lacO$.