Glandular kallikreins are a highly homologous subfamily of serine proteases encoded by 25 genes in the mouse. Several of the gene products have been implicated as having specific roles in growth factor biosynthesis, suggesting a general role for members of this gene family in the generation of biologically active peptides (Mason, A.J., Evans, B.A., Cox, D.R., Shine, J., and Richards, R.I. (1983) Nature 303, 300-307). Here we describe the identification, structure, and expression of the renal kallikrein gene, the major kinin-generating member of the family. Kinins are potent vasodilators implicated in regulation of local blood flow and ion transport. A gene-specific oligodeoxyribonucleotide probe was designed and chemically synthesized from the renal kallikrein gene sequence to distinguish this gene's transcripts from those of other members of the gene family. Differential expression phenotypes were found between the renal kallikrein gene and other members of the kallikrein gene family.