Tandem SAM domain structure of human Caskin1: a presynaptic, self-assembling scaffold for CASK

Structure. 2011 Dec 7;19(12):1826-36. doi: 10.1016/j.str.2011.09.018.


The synaptic scaffolding proteins CASK and Caskin1 are part of the fibrous mesh of proteins that organize the active zones of neural synapses. CASK binds to a region of Caskin1 called the CASK interaction domain (CID). Adjacent to the CID, Caskin1 contains two tandem sterile α motif (SAM) domains. Many SAM domains form polymers so they are good candidates for forming the fibrous structures seen in the active zone. We show here that the SAM domains of Caskin1 form a new type of SAM helical polymer. The Caskin1 polymer interface exhibits a remarkable segregation of charged residues, resulting in a high sensitivity to ionic strength in vitro. The Caskin1 polymers can be decorated with CASK proteins, illustrating how these proteins may work together to organize the cytomatrix in active zones.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry*
  • Animals
  • CHO Cells
  • Cricetinae
  • Guanylate Kinases / chemistry
  • Humans
  • Models, Molecular
  • Nerve Tissue Proteins / chemistry*
  • Surface Plasmon Resonance
  • Synapses / metabolism*


  • Adaptor Proteins, Signal Transducing
  • CASKIN1 protein, human
  • Nerve Tissue Proteins
  • CASK kinases
  • Guanylate Kinases