Partial characterization of a glycoprotein comprising the NH2-terminal region of mouse tumor cell pro-adrenocorticotropic hormone/endorphin.

The glycoprotein accounting for most of the nonadrenocorticotropic hormone (ACTH), non-beta-lipotropin (beta LPH) region of mouse tumor cell pro-ACTH/endorphin was purified from tumor cell culture medium and shown to contain 1/2 cystine residues. Preparations of the 16,000-dalton fragment-related material (referred to as 16K fragment) were heterogeneous with respect to size and charge. Despite this heterogeneity, a partial amino acid sequence for the NH2-terminal region of the molecule was determined by automated Edman degradationof the 16K fragment labeled by reduction and alkylation with [3H]iodoacetic acid or labeled biosynthetically with [3H]tryptophan. The sequence of 1/2 cystine and tryptophan residues in the mouse tumor 16K fragment can be aligned with one region of the amino acid sequence predicted from the cDNA for a bovine precursor to ACTH/beta LPH (Nakanishi, S., Inoue, A., Kita, T., Nakamura, M., Chang, A.C.Y., Cohen, S.N., and Numa, S. (1979) Nature 278, 423--427).