4-Phosphonobutyric acid is primarily used in biochemical research as a competitive inhibitor of enzymes involved in metabolic pathways, particularly those related to glutamate and GABA metabolism. It is often employed in studies to understand the regulation of neurotransmitter synthesis and degradation in the nervous system. Additionally, this compound is utilized in the synthesis of phosphonate-based analogs, which are valuable in medicinal chemistry for developing drugs targeting metabolic disorders or neurological conditions. Its role as a phosphonate derivative also makes it useful in agricultural research, where it can be applied to study plant metabolism and the effects of phosphonate compounds on crop growth and disease resistance.