Cloning and characterization of rat sphingosine kinase 1 with an N-terminal extension.
Sphingosine kinase (SK) is an enzyme that converts sphingosine to sphingosine 1-phosphate, a lysophospholipid with various cellular functions. Here, we report cloning and characterization of a novel isoform of rat SK1 (rSK1) with an N-terminal extension (long-rSK1). Long-rSK1 is 458 amino acid-long and has a calculated molecular weight of 49.8kDa. Deduced amino acid sequences of rat and human long-SK1 have high homology (71.3% identity and 78.9% similarity). Long-rSK1 mRNA is widely expressed throughout the tissues including brain, heart, lung, liver, kidney, and spleen, whereas mRNA encoding rSK1 has been shown not to be expressed in heart or liver. When the long-rSK1 was transfected in COS-7 cells, SK activity was 53-fold increased. Substrate specificity and dependency on divalent cations of long-rSK1 were similar to those of rSK1. Taken together, the fact that long-rSK1 with similar enzymatic characteristics to rSK1 displays differential tissue distribution may suggest an additional role of long-rSK1.
Park
Chang Gyo
CG
Department of Medicine, Division of Allergy and Clinical Immunology, The Johns Hopkins University, School of Medicine, Baltimore, MD 21224, USA.
Lee
Hyun Sil
HS
Lee
Hoi Young
HY
Park
Chang Shin
CS
Choi
Oksoon Hong
OH
D000595:Amino Acid Sequence; D000818:Animals; D002413:Cations, Divalent / Q000378:metabolism; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D000099157:Sphingosine Kinase
D002413:Cations, Divalent; D007527:Isoenzymes; D017853:Phosphotransferases (Alcohol Group Acceptor); D000099157:Sphingosine Kinase