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B Safer

Publications and source records attributed to B Safer.

100 records · Page 6Linked to original sources
PubMed1967

Morphological and biochemical studies of isolated mitochondria from fetal, neonatal, and adult liver and from neoplastic tissues.

A combined morphological and biochemical investigation of mitochondria from developing and rapidly growing tissues ( tumors, fetal, and very early neonatal rat liver) revealed mitochondria which were deficient in respiratory control, showed no valinomycin induced K(+) accumulation or spontaneous Ca(++) uptake, and were unable to undergo a swelling-contraction cycle. Electron microscopic examination of fetal and neonatal livers and a mammary tumor revealed mitochondria which differed from controls with respect to matrix density and ability to undergo reversible structural changes. The importance of isolation and assay media in interpretation of results is emphasized.

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PubMedDate not supplied

The regulation of eIF-2 function protein synthesis initiation.

The regulation of eIF-2 activity during protein synthesis initiation has been postulated to involve phosphorylation/dephosphorylation mechanisms and/or the participation of ancillary protein factors. Both mechanisms would affect directly the binding of initiator methionyl-tRNAi by eIF-2. Recent data concerning the phosphorylation state of eIF-2 in hemin-deficient lysates and other covalent modifications which alter the efficiency of eIF-2 utilization, however, suggest that modulation of eIF-2 activity is more complex, and involves alteration of its catalytic recycling.

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PubMedDate not supplied

Second phosphorylation site on alpha subunit of eIF-2 in rabbit reticulocyte lysate.

Eukaryotic protein synthesis initiation factor 2, eIF-2, was purified from either hemin-supplemented (translationally active) or hemin-deficient (translationally inactive) rabbit reticulocyte lysate under conditions chosen and demonstrated to preserve the in situ phosphorylation state. Direct analysis of the phosphate content of the alpha-subunit of eIF-2 was determined by chemical analysis of the isolated alpha-subunit or by a combination of vertical slab gel isoelectric focusing and immunoblotting. These results were compared with those obtained from an indirect analysis utilising the incorporation of [gamma-32P]ATP into eIF-2 by the heme-sensitive eIF-2 alpha-kinase. All three analyses demonstrate that the phosphorylation site specific for the heme-sensitive kinase is unoccupied in translationally active lysate and 25-30% occupied in translationally inhibited lysate. In addition, both direct analyses support the existence of a second phosphorylation site on the alpha-subunit, not regulated by hemin and distinct from that phosphorylated by the heme-sensitive kinase. Different reticulocyte lysate batches vary with respect to the activity of the kinase responsible for phosphorylation of the second site. Further investigations demonstrated that this kinase is a membrane-associated protein.

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