title: Cell-free synthesis of rat parotid preamylase.
abstract: Poly(A)-containing RNA from rat parotid gland directs the cell-free synthesis of several products in the reticulocyte lysate translation system including a very prominent 58,000-dalton polypeptide which is immunoreactive with anti-alpha-amylase. Purified alpha-amylase has a molecular weight estimated as 56,000 daltons. The 58,000-dalton, cell-free product and alpha-amylase share common peptides as determined by analysis of their limited proteolysis digests. The cross-reactivity and peptide homology suggest that the cell-free product may be a precursor of mature alpha-amylase. While the NH2 terminus of alpha-amylase is blocked, that of the 58,000-dalton product evidently is not, and automated sequence analysis has yielded its partial sequence as: Met-X-Phe-Phe-Leu-Leu-Leu-X-Leu-Ile-X-Leu-X-X-X-X-X-X-X-X-X-Phe-X-X-X-X-X-Ile-X-X-Leu-Phe. The highly hydrophobic nature of the NH2 terminus of the 58,000-dalton, cell-free product suggests that, like other secreted polypeptides, the extra piece may play a role in the transport and secretion of the mature alpha-amylase.
mesh_terms: D000595:Amino Acid Sequence; D000681:Amylases / Q000096:biosynthesis*; D000818:Animals; D002474:Cell-Free System; D004792:Enzyme Precursors / Q000096:biosynthesis*; D010306:Parotid Gland / Q000201:enzymology*; D010446:Peptide Fragments / Q000032:analysis; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D000516:alpha-Amylases / Q000096:biosynthesis*
chemical_list: D004792:Enzyme Precursors; D010446:Peptide Fragments; D012333:RNA, Messenger; D000681:Amylases; D000516:alpha-Amylases