PIN proteins

This article is about auxin transport in plants. For Human gene Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1, see PIN1.
Peptidyl-prolyl cis-trans isomerase Pin1
Identifiers
OrganismArabidopsis thaliana
SymbolPIN1
Entrez816316
PDB1J6Y
RefSeq (mRNA)NM_127360.4
RefSeq (Prot)NP_179395.1
UniProtQ9SL42
Other data
Chromosome2: 7.84 - 7.84 Mb
Search for
StructuresSwiss-model
DomainsInterPro

PIN proteins are integral membrane proteins in plants that transport the anionic form of the hormone auxin across membranes.[1][2] The discovery of the initial member of the PIN gene family, PIN1, occurred through the identification of the pin-formed1 (pin1) mutation in Arabidopsis thaliana. This mutation led to a stem that lacked almost all organs, including leaves and flowers.[3]

Most of the PIN proteins (e.g. PIN1/2/3/4/7 in the model plant Arabidopsis thaliana) localize at the plasma membrane (PM) where they serve as secondary active transporters involved in the efflux of auxin.[4] The PM-localized PIN proteins show asymmetrical localizations on the membrane and are, therefore, responsible for polar auxin transport. Some other members of the PIN family (e.g. PIN5 and 8 in Arabidopsis) localize mostly at the ER-membrane or have a dual PM and ER localization (e.g. PIN6 in Arabidopsis). These PIN proteins regulate the partitioning of auxin within the cell.

The PM-localized PIN proteins physically interact with a few members of the large PGP family of transporters that also work as auxin efflux carriers (PGP1 and PGP19 in Arabidopsis). These interactions result in a synergistic increase in auxin efflux.

The activity and localization of the PM-localized PIN proteins are regulated by several phosphorylations on their large cytosolic hydrophilic loop carried out by kinases of the AGC family (e.g. PID, WAG1, WAG2, PID2 in Arabidopsis) and the D6PK kinase.

  1. ^ Blilou I, Xu J, Wildwater M, Willemsen V, Paponov I, Friml J, et al. (January 2005). "The PIN auxin efflux facilitator network controls growth and patterning in Arabidopsis roots". Nature. 433 (7021): 39–44. Bibcode:2005Natur.433...39B. doi:10.1038/nature03184. hdl:1874/21119. PMID 15635403. S2CID 4414301.
  2. ^ Krecek P, Skupa P, Libus J, Naramoto S, Tejos R, Friml J, Zazímalová E (2009). "The PIN-FORMED (PIN) protein family of auxin transporters". Genome Biology. 10 (12): 249. doi:10.1186/gb-2009-10-12-249. PMC 2812941. PMID 20053306.
  3. ^ Okada K, Ueda J, Komaki MK, Bell CJ, Shimura Y (July 1991). "Requirement of the Auxin Polar Transport System in Early Stages of Arabidopsis Floral Bud Formation". The Plant Cell. 3 (7): 677–684. doi:10.1105/tpc.3.7.677. PMC 160035. PMID 12324609.
  4. ^ Adamowski M, Friml J (January 2015). "PIN-dependent auxin transport: action, regulation, and evolution". The Plant Cell. 27 (1): 20–32. doi:10.1105/tpc.114.134874. PMC 4330589. PMID 25604445.