Disease relevance of PEMT

• ADP-ribosylation of ROS membrane with pertussis toxin, which stabilizes transducin in its inactive state, prevents the light-induced increase in PE N-MTase activity [1].

High impact information on PEMT

• PC substrate arising from the activation of PE N-methyltransferase (PEMT) is hydrolysed by a phospholipase A2 (PLA2), as demonstrated by the accumulation of lysophosphatidylcholine (lyso-PC) [2].
• Both PEMT and PLA2 activities depend on a HDL3 concentration in the range 0-50 micrograms/ml and are strictly dependent on HDL3 binding, because HDL3 modified by tetranitromethane is no longer able to bind to specific receptors and to trigger PEMT and PLA2 activation [2].
• Light activation of phosphatidylethanolamine N-methyltransferase in rod outer segments and its modulation by association states of transducin [1].
• To determine whether the retinal G protein, transducin (Gt), intervenes in the regulation of PE N-MTase in these membranes, the effects of guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) and guanosine 5'-O-(2-thiodiphosphate (GDPbetaS) on the enzyme activity were examined [1].
• Phosphatidylethanolamine N-Methyltransferase (PE N-MTase) is the enzyme responsible for the synthesis of phosphatidylcholine from phosphatidylethanolamine by successive transfer of methyl groups [1].

Biological context of PEMT

• These findings suggest that ROS protein phosphorylation and dephosphorylation modulates PE N-MTase and PLA2 activities in isolated ROS, and that these activities are independently and specifically modulated by particular kinases [3].

Anatomical context of PEMT

• When ROS membranes were selectively depleted of soluble or peripheral and soluble proteins, the PE N-MTase activity remained mainly associated to the membrane, suggesting that this enzyme (s) is an intrinsic membrane protein.(ABSTRACT TRUNCATED AT 400 WORDS)[4]
• Phosphorylation of rod outer segment proteins modulates phosphatidylethanolamine N-methyltransferase and phospholipase A2 activities in photoreceptor membranes [3].

Associations of PEMT with chemical compounds

• The level of PE N-Mtase activity in the purified ROS preparation obtained from crude ROS fractions by discontinuous sucrose gradient centrifugation, was as high as 65% of the level found in the microsomal fraction obtained from the remainder of the retinas [4].
• Phosphatidylethanolamine N-methyltransferase (PE N-MTase) has two pH optima, 8.5 and 10, at low (10 microM) and high (200 microM) SAM concentrations and requires magnesium ions for full activity [4].
• Docosahexaenoic acid, in turn, inhibited PE N-MTase activity at every concentration tested [5].
• Pre-incubation of membranes with the PKC inhibitor H-7 reduced the stimulation of PDBu on PE N-MTase activity, and had no effect on PLA2 activity in ROS membranes incubated with the phorbol ester [3].

References