title: Synthesis of albumin via a precursor protein in cell suspensions from rat liver.
abstract: The mechanism of the biosynthesis of albumin was studied in cell suspensions from rat liver. The cells were prepared by continuous perfusion of the liver in situ with 0.05% collagenase and 0.10% hyaluronidase and incubated under conditions optimized for the incorporation of amino acids into protein. Seven minutes after starting the incubation L-[1-14C]leucine was added, followed after 25 min by a 15  or 30-min chase with an 830-fold excess of non-radioactive L-leucine. Total protein, an albumin-like protein, and albumin were isolated from samples withdrawn immediately of total protein was found to remain constant after addition of the non-radioactive L-leucine, whereas that of the albumin-like protein decreased and that of albumin increased with incubation time. The increase in albumin radioactivity accounted for the decrease in radioactivity of the albumin-like protein, suggesting that the latter is a precursor of albumin. The precursor protein differed from albumin by an oligopeptide extension at the N-terminal end.
mesh_terms: D000418:Albumins / Q000096:biosynthesis*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008861:Microsomes / Q000378:metabolism; D008970:Molecular Weight; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats
chemical_list: D000418:Albumins; D000596:Amino Acids; D011498:Protein Precursors; D007930:Leucine