Fig. 5.

Dynamic changes in the activity and subunit composition of SPT in the early postnatal rat brain. A: SPT activity was measured using an HPLC-ESI-MS/MS method combined with deuterated serine to quantitatively measure 3-KDS generated in membranes from postnatal rat brains. Data are graphed as picomoles of 3-KDS lipid per milligram of total protein. Data are expressed as mean ± SEM, n = 5 animals per age group. B: Western blot analysis of total membranes isolated from the brains of postnatal rats of various ages as indicated in each panel. Blots were probed with primary antibodies for the large subunits of SPT (SPTLC1-3), total ORMDL protein, and calnexin.