A temperature-sensitive mammalian cell mutant with thermolabile serine palmitoyltransferase for the sphingolipid biosynthesis.

A temperature-sensitive mammalian cell mutant with thermolabile serine palmitoyltransferase for the sphingolipid biosynthesis.

We devised an in situ assay method for the activity of serine palmitoyltransferase (SPT) that catalyzes the first step in sphingolipid biosynthesis and isolated a temperature-sensitive mutant of Chinese hamster ovary cells with thermolabile SPT. This mutant stopped growing at 40 degrees C after several generations, although the cells grew at 33 and 37 degrees C at rates similar to those of the ...

Temperature-sensitive RNA polymerase of a mammalian cell mutant.

In our attempts to characterize a temperature-sensitive mutant (ts-2) of monkey kidney cell line BSC-i, we have provided evidence to show that the mutant was defective in the synthesis or processing of rRNA (45, 28 and 18 s) molecules at 39-5 °C and there was indication that the nucleolar RNA polymerase (I) or some factor associated with its functional activity was thermolabile at the restricte...

A mammalian cell mutant with a temperature-sensitive leucyl-transfer RNA synthetase.

A cell mutant of the Chinese hamster ovary line, which is temperature sensitive for protein synthesis, is specifically defective in vivo in its ability to charge tRNA with leucine. Cytoplasmic extracts exhibited temperature-sensitive leucyl-tRNA synthetase activity. It is, therefore, highly likely that the mutant has a structural alteration in leucyl-tRNA synthetase. The low leakiness and low r...

cis-4-Methylsphingosine decreases sphingolipid biosynthesis by specifically interfering with serine palmitoyltransferase activity in primary cultured neurons.

The effect of six different structurally modified sphingosine analogues on biosynthesis of sphingolipids was studied in primary cultured murine cerebellar neurons. Treatment of cells with cis-4-methylsphingosine at micromolar levels resulted in a markedly decreased sphingolipid biosynthesis, whereas the other compounds examined, trans-4-methylsphingosine, cis-5-methylsphingosine, trans-5-methyl...

Defining the Roles of Serine Palmitoyltransferase-Interacting Proteins in the Regulation of Sphingolipid Homeostasis