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Biomedical subjects

A B Lerner

Publications and source records attributed to A B Lerner.

At least 91 records · Page 5Linked to original sources
PubMed1974

Regulation of melanocyte stimulating hormone action at the receptor level: discontinuous binding of hormone to synchronized mouse melanoma cells during the cell cycle.

Melanocyte stimulating hormone coupled to Sepharose effects an increase in tryosinase (EC 1.14.18.1; monophenol monoxygenase) activity of cultivated mouse melanoma cells. Synchronized cells are found to respond to melanocyte stimulating hormone only in the G2 phase of the cell cycle, although their response to cyclic AMP is independent of position in the cell cycle. The binding of (125)I-labeled melanocyte stimulating hormone occurs predominantly in G2. These observations are satisfied by a model in which the hormone can activate adenylate cyclase (EC 4.6.1.1) by binding to a melanocyte stimulating hormone receptor only in G2; the events distal to cyclic AMP production can occur throughout the cell cycle.

Animals↗
PubMed1974

Neuromelanin.

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Brain↗
PubMed1971

Racemization of alpha-melanotropin.

Racemization of the amino acid residues of alpha-melanotropin was measured after exposure of the peptide to alkali for various lengths of time. Rates of racemization were then compared to the rate of transformation by alkali of alpha-melanotropin into a hormone with prolonged melanotropic activity. When in vitro prolongation became maximal, serine, methionine, histidine, phenylalanine and arginine were racemized 50-70%, glutamic acid, tyrosine and tryptophan 30-40% and lysine, proline and valine 10% or less. Racemization of a particular amino acid residue in alpha-melanotropin could not be associated with induction of prolongation of activity. Rather, partial racemization at multiple sites in the molecule seems almost as effective as extensive or total racemization of a single residue in producing a hormone with prolonged biological effects.

Amino Acids↗