The individual isoforms of ORMDL, the regulatory subunit of serine palmitoyltransferase, have distinctive sensitivities to ceramide.

Sphingolipids play crucial roles in cell membrane structure and in multiple signaling pathways. Sphingolipid de novo biosynthesis is mediated by the serine palmitoyltransferase (SPT) enzyme complex. Homeostatic regulation of this complex is dependent on its regulatory subunit, the ORMDLs, of which there are three isoforms.

The individual isoforms of ORMDL, the regulatory subunit of serine palmitoyltransferase, have distinctive sensitivities to ceramide.

Unlabelled: Sphingolipids play crucial roles in cell membrane structure and in multiple signaling pathways. Sphingolipid biosynthesis is mediated by the serine palmitoyltransferase (SPT) enzyme complex. Homeostatic regulation of this complex is dependent on its regulatory subunit, the ORMDLs, of which there are three isoforms.

Preparation of HeLa Total Membranes and Assay of Lipid-inhibition of Serine Palmitoyltransferase Activity.

Serine palmitoyltranferase (SPT) is a pyridoxal 5' phosphate (PLP)-dependent enzyme that catalyzes the first and rate-limiting step of synthesis of sphingolipids. SPT activity is homeostatically regulated in response to increased levels of sphingolipids. This homeostatic regulation of SPT is mediated through small ER membrane proteins termed the ORMDLs.