SS4 starch synthase 4 [Arabidopsis thaliana (thale cress)] - Gene

Summary

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Gene symbol: SS4
Gene description: starch synthase 4
Primary source: Araport:AT4G18240
Locus tag: AT4G18240
Gene type: protein coding
RefSeq status: REVIEWED
Organism: Arabidopsis thaliana (ecotype: Columbia)
Lineage: Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta; Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae; rosids; malvids; Brassicales; Brassicaceae; Camelineae; Arabidopsis
Also known as: ARABIDOPSIS THALIANA STARCH SYNTHASE 4; ATSS4; SSIV; starch synthase 4; STARCH SYNTHASE 4; T9A21.90; T9A21_90
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Genomic context

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Location:: chromosome: 4

Exon count:: 16

Sequence:: Chromosome: 4; NC_003075.7 (10082108..10087203)

Chromosome 4 - NC_003075.7 Genomic Context describing neighboring genes

Genomic regions, transcripts, and products

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Go to reference sequence details

Genomic Sequence:: NC_003075.7

Go to nucleotide: Graphics FASTA GenBank

Bibliography

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GeneRIFs: Gene References Into Functions

What's a GeneRIF?

Results indicate that plastidal phosphorylase (PHS1) and starch synthase 4 (SS4) are differently involved in starch granule formation and do not act in series.
Title: Starch Synthase 4 and Plastidal Phosphorylase Differentially Affect Starch Granule Number and Morphology.
the N-terminal part of SS4 serves to establish the correct granule morphology by properly localizing this activity.
Title: Distinct Functions of STARCH SYNTHASE 4 Domains in Starch Granule Formation.
SS4 plays a key role in granule initiation, allowing it to proceed in a way that avoids premature degradation of primers by starch hydrolases, such as AMY3.
Title: Degradation of Glucan Primers in the Absence of Starch Synthase 4 Disrupts Starch Granule Initiation in Arabidopsis.
SS4 forms dimers, which depends on a region located between the coiled-coil region and the glycosyltransferase domain of SS4. This region is highly conserved between all SS4 enzymes sequenced to date. We show that the dimerization seems to be necessary for the activity of the enzyme.
Title: The N-terminal Part of Arabidopsis thaliana Starch Synthase 4 Determines the Localization and Activity of the Enzyme.
SS4 is an essential component of a mechanism that coordinates granule formation with chloroplast division during leaf expansion.
Title: Starch synthase 4 is essential for coordination of starch granule formation with chloroplast division during Arabidopsis leaf expansion.
Overexpression of SSIV induces the accumulation of starch in Arabidopsis.
Title: Enhancing the expression of starch synthase class IV results in increased levels of both transitory and long-term storage starch.
The data point to a complex mechanism for starch granule formation and to the different abilities of SSIV and SSIII to support this process in Arabidopsis leaves.
Title: Starch granule initiation in Arabidopsis requires the presence of either class IV or class III starch synthases.
In mutants the number of starch granules per plastid dramatically decreased leading to a large increase in their size.
Title: The phenotype of soluble starch synthase IV defective mutants of Arabidopsis thaliana suggests a novel function of elongation enzymes in the control of starch granule formation.

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Interactions

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Products	Interactant	Other Gene	Complex	Source	Pubs	Description

General gene information

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Homology

Orthologs from OrthoDB

NM_117934.4

Supported by ESTs:

Gene Ontology Provided by TAIR

Function	Evidence Code	Pubs
enables alpha-1,4-glucan synthase activity	IEA Inferred from Electronic Annotation more info
enables glycogen (starch) synthase activity	IEA Inferred from Electronic Annotation more info
enables glycosyltransferase activity	ISS Inferred from Sequence or Structural Similarity more info
enables protein binding	IPI Inferred from Physical Interaction more info	PubMed
enables starch synthase activity	IMP Inferred from Mutant Phenotype more info	PubMed

Process	Evidence Code	Pubs
involved_in starch biosynthetic process	IEA Inferred from Electronic Annotation more info
acts_upstream_of_or_within starch metabolic process	IMP Inferred from Mutant Phenotype more info	PubMed

Component	Evidence Code	Pubs
located_in chloroplast	HDA more info	PubMed
located_in chloroplast	IDA Inferred from Direct Assay more info	PubMed
located_in chloroplast	ISM Inferred from Sequence Model more info

General protein information

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Preferred Names: starch synthase 4

NP_193558.3

starch synthase 4 (SS4); FUNCTIONS IN: transferase activity, transferring glycosyl groups; INVOLVED IN: starch metabolic process; LOCATED IN: chloroplast; EXPRESSED IN: 24 plant structures; EXPRESSED DURING: 13 growth stages; CONTAINS InterPro DOMAIN/s: Glycogen/starch synthases, ADP-glucose type (InterPro:IPR011835), Starch synthase, catalytic domain (InterPro:IPR013534), Glycosyl transferase, group 1 (InterPro:IPR001296); BEST Arabidopsis thaliana protein match is: starch synthase 3 (TAIR:AT1G11720.1); Has 55451 Blast hits to 38117 proteins in 4040 species: Archae - 1014; Bacteria - 10985; Metazoa - 22418; Fungi - 3875; Plants - 6050; Viruses - 242; Other Eukaryotes - 10867 (source: NCBI BLink).