Prokaryotic expression of bovine lactoferrin deletion mutants that bind to the Ca2+-dependent lactoferrin receptor on isolated rat hepatocytes.

We generated a series of recombinant variants of bovine lactoferrin (Lf) as fusion proteins using two prokaryotic expression vectors and examined the ability of the expressed proteins to compete with native Lf for binding to the Ca2+-dependent Lf receptor on isolated rat hepatocytes. A near-full-length bovine Lf cDNA (pN16b) was expressed in pGEMEX-2 as a gene 10 fusion protein (r-bLf10/-70). Deletions of pN16b were cloned into the HindIII/NotI and BamHI/NotI restriction sites of expression vector pET 32 and expressed as thioredoxin fusion proteins, r-bLfT/-271 and r-bLfT/-310, respectively.

Isolated rat hepatocytes differentially bind and internalize bovine lactoferrin N- and C-lobes.

Isolated rat hepatocytes bind and internalize bovine lactoferrin (Lf) and its bound iron in a Ca2+-dependent manner. In this study, we determined if one or both halves of Lf (N- and C-lobes) were responsible for the interaction of Lf with hepatocytes. We isolated three tryptic fragments of bovine Lf.

Nyctohemeral rhythm in the levels of S-adenosylmethionine in the rat pineal gland and its relationship to melatonin biosynthesis.

Liquid chromatographic techniques that permit the simultaneous analysis of S-adenosylmethionine, melatonin, and its intermediary metabolites N-acetyl-5-hydroxytryptamine and 5-hydroxytryptamine within individual pineal glands have been developed. S-Adenosylmethionine has been shown to undergo a marked nyctohemeral rhythm in the pineal gland of the rat, with maximal levels occurring during the light period and minimal levels during the dark period. Detailed studies of the temporal relationships between the levels of S-adenosylmethionine and those of melatonin and its intermediary metabolites suggest that an association exists between the levels of S-adenosylmethionine and the status of the biosynthesis of melatonin.

Endocytosis and degradation of bovine apo- and holo-lactoferrin by isolated rat hepatocytes are mediated by recycling calcium-dependent binding sites.

We characterized endocytosis of iron-saturated (holo) and iron-depleted (apo) 125I-labeled bovine lactoferrin (Lf) by isolated rat hepatocytes. Hepatocytes ingested both Lf forms--determined by EGTA/dextran sulfate removal of surface-bound Lf--at maximal endocytic rates of 1.85 and 1.