PTDSS1 - Phosphatidylserine synthase 1 - human protein (Function)
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PTDSS1 »  Phosphatidylserine synthase 1   [ EC ]  (PSS-1)
Protein also known as:  Serine-exchange enzyme I.
Gene name:  PTDSS1
Entry whose protein(s) existence is based on evidence at protein level
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Catalyzes a base-exchange reaction in which the polar head group of phosphatidylethanolamine (PE) or phosphatidylcholine (PC) is replaced by L-serine. In membranes, PTDSS1 catalyzes mainly the conversion of phosphatidylcholine. Also converts, in vitro and to a lesser extent, phosphatidylethanolamine.  
  • CuratedUniProtKB
GO molecular function 
Transferase activitydefinition[GO:0016740]  
  • IEAUniProtKB KW
GO biological process 
Phosphatidylserine biosynthetic processdefinition[GO:0006659]  
  • IEAUniPathway
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC L-1-phosphatidylethanolamine + L-serine L-1-phosphatidylserine + ethanolamine.  
  • CuratedUniProtKB
It is regulated in the following manner
Requires calcium ions. Activated by exogenous phosphatidylethanolamine.  
  • CuratedUniProtKB
This protein is involved in the following pathway
According to KEGG, this protein belongs to the following pathways:
Glycerophospholipid metabolism  hsa00564+9791  
Metabolic pathways  hsa01100+9791  
According to Reactome, this protein belongs to the following pathway:
Synthesis of PS  REACT_120823  
More information is available from:

Biophysicochemical properties

Kinetic parameters
KM 67 uM for serine (in the presence of 2 mM PC)
KM 24 uM for serine (in the presence of 1 mM PE)
pH Optimum pH for both PC and PE is between 7.0 and 7.5.


Biological process 
Lipid biosynthesis  definition   [KW-0444]
Lipid metabolism  definition   [KW-0443]
Phospholipid biosynthesis  definition   [KW-0594]
Phospholipid metabolism  definition   [KW-1208]
Molecular function 
Transferase  definition   [KW-0808]
Technical term 
Reference proteome  definition   [KW-1185]

Further external links

GenomeRNAi: 9791
PRO: PR:P48651