Hemokinin 1 (HK1) is an 11 amino acid tachykinin produced by the proteolytic processing of a 128 amino acid precursor, preprotachykinin C. This peptide has been shown to bind the neurokinin-1 receptor (NK-1r) with the same affinity and potency as substance P. The NK-1r has been implicated in a number of conditions such as hyperalgesia and chronic pain. Hemokinin 1 and the natural ligand for the NK-1r, substance P, have been shown to have equivalent binding to the receptor. The NK-1r is involved with respiratory rhythm, mood disorders, anxiety and stress, and reinforcement. One of the most important roles for NK-1r is in the spinal cord in the transmission of pain signals from peripheral pain receptors to the brain. NK-1r pathway is implicated in the establishment and maintenance of a chronic pain state.
Hemokinin 1-SAP (HK1-SAP) is a chemical conjugate of the hemokinin-1 peptide and the ribosome-inactivating protein, saporin. It eliminates cells expressing the neurokinin-1 receptor (NK-1r). All other cells are left untouched, even when they are the predominant cell type.