Distinct Rab27A binding affinities of Slp2-a and Slac2-a/melanophilin: Hierarchy of Rab27A effectors

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The small GTPase Rab27A has recently been shown to regulate melanosome transport in mammalian skin melanocytes through sequentially interacting with two Rab27A effectors, Slac2-a/melanophilin and Slp2-a. Although Slac2-a and Slp2-a contain a similar N-terminal Rab27A-binding domain (named SHD, Slp homology domain), nothing is known about the functional differences between the Slac2-a SHD and Slp2-a SHD. In this study, the Rab27A-binding affinity of ten putative Rab27A effector proteins has been investigated. It has been found that they could be classified into a low-affinity group (e.g., Slac2-a) and a high-affinity group (e.g., Slp2-a and Slp4-a) based on their Rab27A-binding affinity. Kinetic analysis of the GTP-Rab27A-binding to the SHD of Slp2-a, Slp4-a, and Slac2-a by surface plasmon resonance further indicated that the kinetic parameters of Rab27A for the Slp2-a SHD, Slp4-a SHD, and Slac2-a SHD consisted of a fast association rate constant (3.35 × 104, 2.06 × 104, and 2.11 × 104 M-1 s -1, respectively) and a slow dissociation rate constant (4.48 × 10-4, 3.96 × 10-4, and 2.37 × 10-3 s-1 respectively), and their equilibrium dissociation constants were determined to be 13.4, 19.2, and 112 nM, respectively. Our data suggest that distinct Rab27A binding activities of Slac2-a and Slp2-a ensure the order (or hierarchy) of Rab27A effectors that sequentially function in melanosome transport in melanocytes.

Original languageEnglish
Pages (from-to)666-674
Number of pages9
JournalBiochemical and biophysical research communications
Volume343
Issue number2
DOIs
Publication statusPublished - 2006 May 5
Externally publishedYes

Keywords

  • Griscelli syndrome
  • Melanosome transport
  • Rab-binding domain
  • Rab27A effector
  • Slac2-a/melanophilin
  • Slp2-a
  • Surface plasmon resonance
  • Synaptotagmin

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Distinct Rab27A binding affinities of Slp2-a and Slac2-a/melanophilin: Hierarchy of Rab27A effectors'. Together they form a unique fingerprint.

Cite this