The complete amino acid sequence of the gamma-subunit of mouse submaxillary gland 7 S nerve growth factor has been determined from analyses of the peptides generated by cyanogen bromide, trypsin, and chymotrypsin from the naturally occurring fragments. All peptides were sequenced automatically in a spinning-cup sequenator using Polybrene to minimize extractive losses by the solvents employed thoughout the degradation cycles. The gamma-subunit, a serine protease with arginine specificity, contains 233 amino acid residues and shares sequence homology with other proteases of this family. The five disulfide bonds of the gamma-subunit are a subset of the six disulfides present in bovine trypsin, as judged by the location of the half-cystine residues in the primary structure. An N-linked carbohydrate side chain is attached to Asn-78 in at least a majority of tee gamma-molecules.