KCS1/YDR017C Summary Help

Standard Name KCS1 1
Systematic Name YDR017C
Feature Type ORF, Verified
Description Inositol hexakisphosphate and inositol heptakisphosphate kinase; generation of high energy inositol pyrophosphates by Kcs1p is required for many processes such as vacuolar biogenesis, stress response, and telomere maintenance; inositol hexakisphosphate is also known as IP6; inositol heptakisphosphate is also known as IP7 (2, 3, 4, 5 and see Summary Paragraph)
Name Description pKC1 Suppressor 1
Chromosomal Location
ChrIV:482267 to 479115 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All KCS1 GO evidence and references
  View Computational GO annotations for KCS1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Regulators 1 genes
Classical genetics
Large-scale survey
297 total interaction(s) for 277 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 15
  • Reconstituted Complex: 1
  • Two-hybrid: 1

Genetic Interactions
  • Dosage Lethality: 1
  • Negative Genetic: 219
  • Phenotypic Enhancement: 1
  • Phenotypic Suppression: 2
  • Positive Genetic: 42
  • Synthetic Growth Defect: 4
  • Synthetic Lethality: 6
  • Synthetic Rescue: 5

Expression Summary
Length (a.a.) 1,050
Molecular Weight (Da) 119,549
Isoelectric Point (pI) 6.78
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrIV:482267 to 479115 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..3153 482267..479115 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000002424

KCS1 encodes one of two yeast inositol pyrophosphate synthases (also known as inositol hexakisphophate kinases; IP6Ks); the other is encoded by VIP1. The inositol pyrophosphates (PP-IPs) produced by Kcs1p and/or Vip1p serve as high-energy signaling molecules involved in such diverse processes as vacuolar biogenesis, the stress response, DNA repair, cell wall synthesis, telomere maintenance, and phosphate homeostasis (see 5, 6, 7, and references therein).

Both enzymes catalyze the addition of beta-phosphate to the fully phosphorylated six-carbon ring of inositol hexakisphosphate (IP6). However, these enzymes produce different isomers of diphosphoinositol pentakisphosphate (IP7). Kcs1p phosphorylates IP6 at the C5 position forming 5PP-IP5, and Vip1p phosphorylates IP6 at the C4 or C6 position forming 4PP-IP5 or 6PP-IP5, respectively (the exact phosphorylation position has not yet been determined). The different IP7 isomers are biologically relevant: the Kcs1p product cannot substitute for the Vip1p product during phosphate homeostasis (8). Kcs1p and Vip1p also work in concert to produce bis-diphosphoinositol tetrakisphosphate ([PP]2-IP4; IP8). Kcs1p phosphorylates the Vip1p IP7 product 4/6PP-IP5, and Vip1p phosphorylates the Kcs1p IP7 product 5PP-IP5 (4).

Although Kcs1p function has been best characterized on the IP6 and IP7 substrates, this enzyme has also been demonstrated to possess kinase activity on a number of other inositol phosphates substrates that do not have a full complement of alpha-phosphorylation, including I(1,4,5)P3 (3), I(1,3,4,5)P4 (3), I(1,3,4,5,6,)P5 (2), and PP-IP4 (2). The physiological relevance of these reactions is unclear at this time.

Inositol pyrophosphate synthases are highly conserved and found across eukaryotes. In humans, three Kcs1p-like enzymes (IHPK1/IP6K1, IP6K2/IP6K2, IP6K3/IP6K3) (9, 10) and two Vip1p-like enzymes (HISPPD2a/PPIP5K1/VIP1 and PPIP5K2/VIP2) (11, 12) have been identified.

Last updated: 2008-01-22 Contact SGD

References cited on this page View Complete Literature Guide for KCS1
1) Huang KN and Symington LS  (1995) Suppressors of a Saccharomyces cerevisiae pkc1 mutation identify alleles of the phosphatase gene PTC1 and of a novel gene encoding a putative basic leucine zipper protein. Genetics 141(4):1275-85
2) Saiardi A, et al.  (2000) The inositol hexakisphosphate kinase family. Catalytic flexibility and function in yeast vacuole biogenesis. J Biol Chem 275(32):24686-92
3) Dubois E, et al.  (2002) In Saccharomyces cerevisiae, the inositol polyphosphate kinase activity of Kcs1p is required for resistance to salt stress, cell wall integrity, and vacuolar morphogenesis. J Biol Chem 277(26):23755-63
4) Mulugu S, et al.  (2007) A conserved family of enzymes that phosphorylate inositol hexakisphosphate. Science 316(5821):106-9
5) Bennett M, et al.  (2006) Inositol pyrophosphates: metabolism and signaling. Cell Mol Life Sci 63(5):552-64
6) Onnebo SM and Saiardi A  (2007) Inositol pyrophosphates get the vip1 treatment. Cell 129(4):647-9
7) Bhandari R, et al.  (2007) Inositol pyrophosphate pyrotechnics. Cell Metab 5(5):321-3
8) Lee YS, et al.  (2007) Regulation of a cyclin-CDK-CDK inhibitor complex by inositol pyrophosphates. Science 316(5821):109-12
9) Saiardi A, et al.  (1999) Synthesis of diphosphoinositol pentakisphosphate by a newly identified family of higher inositol polyphosphate kinases. Curr Biol 9(22):1323-6
10) Saiardi A, et al.  (2001) Identification and characterization of a novel inositol hexakisphosphate kinase. J Biol Chem 276(42):39179-85
11) Fridy PC, et al.  (2007) Cloning and Characterization of Two Human VIP1-like Inositol Hexakisphosphate and Diphosphoinositol Pentakisphosphate Kinases. J Biol Chem 282(42):30754-62
12) Choi JH, et al.  (2007) Purification, sequencing, and molecular identification of a mammalian PP-InsP5 kinase that is activated when cells are exposed to hyperosmotic stress. J Biol Chem 282(42):30763-75