Literature summary for 2.3.1.50 extracted from

Kimberlin, A.N.; Majumder, S.; Han, G.; Chen, M.; Cahoon, R.E.; Stone, J.M.; Dunn, T.M.; Cahoon, E.B.
Arabidopsis 56-amino acid serine palmitoyltransferase-interacting proteins stimulate sphingolipid synthesis, are essential, and affect mycotoxin sensitivity (2013), Plant Cell, 25, 4627-4639.

Activating Compound

Activating Compound	Comment	Organism	Structure
small subunits of serine palmitoyltransferase	isoforms ssSPTa and ssSPTb, UniProt A8MSB8 and F4IPU5, strongly stimulate SPT activity. Small subunit ssSPTa transcripts are more enriched in all organs and over 400fold more abundant in pollen than small subunit ssSPTb transcripts. Homozygous ssSPTa T-DNA mutants are not recoverable, and 50% nonviable pollen is detected in heterozygous ssspta mutants. The small subunits are essential for male gametophytes, are important for mycotoxin fumonisin B1 sensitivity, and limit sphingolipid synthesis in planta	Arabidopsis thaliana

Cloned(Commentary)

Cloned (Comment)	Organism
recombinant expression of FLAG-tagged enzyme subunit LCB1 and of Myc-tagged enzyme subunit LCB2 in Saccharomyces cerevisiae microsomes. Expressing the Arabidopsis thaliana LCB1/LCB2 heterodimers has very low SPT activity, whereas coexpression of Arabidopsis thaliana ssSPTs, ssSPTa and ssSPTb, derived 56-amino acid polypeptides in a Saccharomyces cerevisiae enzyme SPT null mutant and stimulate SPT enzyme activity of the Arabidopsis LCB1/LCB2 heterodimer by over 100fold through physical interaction with LCB1/LCB2. Transient Agrobacterium tumefaciens-mediated transformation of Nicotiana benthaminana with YFP-labeled small subunits of serine palmitoyltransferase, ssSPTa and ssSPTb	Arabidopsis thaliana

Cloned (Comment)

Organism

recombinant expression of FLAG-tagged enzyme subunit LCB1 and of Myc-tagged enzyme subunit LCB2 in Saccharomyces cerevisiae microsomes. Expressing the Arabidopsis thaliana LCB1/LCB2 heterodimers has very low SPT activity, whereas coexpression of Arabidopsis thaliana ssSPTs, ssSPTa and ssSPTb, derived 56-amino acid polypeptides in a Saccharomyces cerevisiae enzyme SPT null mutant and stimulate SPT enzyme activity of the Arabidopsis LCB1/LCB2 heterodimer by over 100fold through physical interaction with LCB1/LCB2. Transient Agrobacterium tumefaciens-mediated transformation of Nicotiana benthaminana with YFP-labeled small subunits of serine palmitoyltransferase, ssSPTa and ssSPTb

Arabidopsis thaliana

Protein Variants

Protein Variants	Comment	Organism
additional information	T-DNA disruption of ssSPTa results in loss of pollen viability	Arabidopsis thaliana

Inhibitors

Inhibitors	Comment	Organism	Structure
mycotoxin fumonisin B1	enzyme sensitivity to the inhibitor is increased by small subunit ssSPTa overexpression	Arabidopsis thaliana

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
microsome	-	Arabidopsis thaliana	-	-

Organism

Organism	UniProt	Comment	Textmining
Arabidopsis thaliana	-	-	-

Source Tissue

Source Tissue	Comment	Organism	Textmining
pollen	small subunit ssSPTa transcripts are more enriched in all organs and over 400fold more abundant in pollen than small subunit ssSPTb transcripts	Arabidopsis thaliana	-

Subunits

Subunits	Comment	Organism
heterodimer	serine palmitoyltransferase is composed of LCB1 and LCB2 subunits	Arabidopsis thaliana

Synonyms

Synonyms	Comment	Organism
serine palmitoyltransferase	-	Arabidopsis thaliana
SPT	-	Arabidopsis thaliana

General Information

General Information	Comment	Organism
malfunction	homozygous ssSPTa T-DNA mutants are not recoverable, and 50% nonviable pollen is detected in heterozygous ssSpta mutants. Pollen viability is recovered by expression of wild-type ssSPTa or ssSPTb under control of the ssSPTa promoter, indicating ssSPTa and ssSPTb functional redundancy. SPT activity and sensitivity to the PCD-inducing mycotoxin fumonisin B1 are increased by ssSPTa overexpression. Conversely, SPT activity and mycotoxin fumonisin B1 sensitivity are reduced in ssSPTa RNA interference lines	Arabidopsis thaliana
metabolism	serine palmitoyltransferase, composed of LCB1 and LCB2 subunits, catalyzes the primary regulatory point for sphingolipid synthesis	Arabidopsis thaliana
physiological function	enzyme activators, the small subunits are essential for male gametophytes, are important for mycotoxin fumonisin B1 sensitivity, and limit sphingolipid synthesis in planta	Arabidopsis thaliana