Penicillin-binding proteins (PBPs) are a class of bacterial proteins, including various subtypes such as PBP1 to PBP6. These proteins have a transmembrane structure and are primarily located in the bacterial cell wall. PBPs play a central role in the synthesis and remodeling of the cell wall, particularly in the cross-linking of peptidoglycan. By inhibiting PBPs, penicillin antibiotics can block cell wall synthesis, leading to bacterial death. Mutations in PBP genes may lead to antibiotic resistance.