This review discusses the role of the Phosphotransferase System (PTS) and its regulatory proteins in carbohydrate metabolism and carbon catabolite repression (CCR) in bacteria. The PTS is a key system for the uptake and phosphorylation of carbohydrates, and its regulation is crucial for bacterial growth and metabolism. The review highlights the importance of the PTS in CCR, where the availability of a preferred carbon source represses the synthesis of enzymes for the utilization of alternative carbon sources. The PTS components, including EI ( Enzyme I), HPr, and EII ( Enzyme II), are described in detail, along with their structural characteristics and functional roles. The review also explores the regulatory mechanisms involving the PTS, such as inducer exclusion, where unphosphorylated EIIA^Glc blocks the import of certain substrates and inhibits their metabolism. The role of EIIA^Glc in modulating adenylate cyclase activity and the subsequent effects on CCR are discussed, along with the involvement of global regulators like Crp/cAMP in these processes. The review emphasizes the complex interplay between PTS components, metabolic state, and regulatory proteins in controlling carbohydrate metabolism and CCR in both gram-negative and gram-positive bacteria.This review discusses the role of the Phosphotransferase System (PTS) and its regulatory proteins in carbohydrate metabolism and carbon catabolite repression (CCR) in bacteria. The PTS is a key system for the uptake and phosphorylation of carbohydrates, and its regulation is crucial for bacterial growth and metabolism. The review highlights the importance of the PTS in CCR, where the availability of a preferred carbon source represses the synthesis of enzymes for the utilization of alternative carbon sources. The PTS components, including EI ( Enzyme I), HPr, and EII ( Enzyme II), are described in detail, along with their structural characteristics and functional roles. The review also explores the regulatory mechanisms involving the PTS, such as inducer exclusion, where unphosphorylated EIIA^Glc blocks the import of certain substrates and inhibits their metabolism. The role of EIIA^Glc in modulating adenylate cyclase activity and the subsequent effects on CCR are discussed, along with the involvement of global regulators like Crp/cAMP in these processes. The review emphasizes the complex interplay between PTS components, metabolic state, and regulatory proteins in controlling carbohydrate metabolism and CCR in both gram-negative and gram-positive bacteria.