Serine palmitoyltransferase subunit 1 is present in the endoplasmic reticulum, nucleus and focal adhesions, and functions in cell morphology.
Serine palmitoyltransferase (SPT) has been localized to the endoplasmic reticulum (ER) by subcellular fractionation and enzymatic assays, and fluorescence microscopy of epitope-tagged SPT; however, our studies have suggested that SPT subunit 1 might be present also in focal adhesions and the nucleus. These additional locations have been confirmed by confocal microscopy using HEK293 and HeLa cells, and for focal adhesions by the demonstration that SPT1 co-immunoprecipitates with vinculin, a focal adhesion marker protein. The focal adhesion localization of SPT1 is associated with cell morphology, and possibly cell migration, because it is seen in most cells before they reach confluence but disappears when they become confluent, and is restored by a standard scratch-wound healing assay. Conversely, elimination of SPT1 using SPTLC1 siRNA causes cell rounding. Thus, in addition to its "traditional" localization in the ER for de novo sphingolipid biosynthesis, SPT1 is present in other cellular compartments, including focal adhesions where it is associated with cell morphology.
Petit Institute for Bioengineering and Bioscience, Atlanta, GA 30332, USA.
Jia
J
Wei
Tokunbo
T
Yerokun
Martina
M
Leipelt
Chris A
CA
Haynes
Harish
H
Radhakrishna
Amin
A
Momin
Samuel
S
Kelly
Hyejung
H
Park
Elaine
E
Wang
Jill M
JM
Carton
David J
DJ
Uhlinger
Alfred H
AH
Merrill
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D002467:Cell Nucleus / Q000201:enzymology*; D048430:Cell Shape; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D022001:Focal Adhesions / Q000201:enzymology*; D020868:Gene Silencing; D006801:Humans; D047468:Immunoprecipitation; D021122:Protein Subunits / Q000378:metabolism*; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000378:metabolism; D015203:Reproducibility of Results; D051102:Serine C-Palmitoyltransferase / Q000378:metabolism*; D013107:Sphingolipids / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology; D016596:Vinculin / Q000378:metabolism
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; D021122:Protein Subunits; D034741:RNA, Small Interfering; D013107:Sphingolipids; D016596:Vinculin; D051102:Serine C-Palmitoyltransferase