Pcp4l1 contains an auto-inhibitory element that prevents its IQ motif from binding to calmodulin

Marc Alard Morgan, James I. Morgan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Purkinje cell protein 4-like 1 (Pcp4l1) is a small neuronal IQ motif protein closely related to the calmodulin-binding protein Pcp4/PEP-19. PEP-19 interacts with calmodulin via its IQ motif to inhibit calmodulin-dependent enzymes and we hypothesized Pcp4l1 would have similar properties. Surprisingly, full-length Pcp4l1 does not interact with calmodulin in yeast two-hybrid or pulldown experiments yet a synthetic peptide constituting only the IQ motif of Pcp4l1 binds calmodulin and inhibits calmodulin-dependent kinase II. A nineresidue glutamic acid-rich sequence in Pcp4l1 confers these unexpected properties. This element lies outside the IQ motif and its deletion or exchange with the homologous region of PEP-19 restores calmodulin binding. Conversion of a single isoleucine (Ile36) within this motif to phenylalanine, the residue present in PEP-19, imparts calmodulin binding onto Pcp4l1. Moreover, only aromatic amino acid substitutions at position 36 in Pcp4l1 allow binding. Thus, despite their sequence similarities PEP-19 and Pcp4l1 have distinct properties with the latter harboring an element that can functionally suppress an IQ motif. We speculate Pcp4l1 may be a latent calmodulin inhibitor regulated by post-translational modification and/or co-factor interactions.

Original languageEnglish (US)
Pages (from-to)843-851
Number of pages9
JournalJournal of neurochemistry
Issue number6
StatePublished - Jun 2012


  • Calcium
  • Calmodulin
  • IQ motif
  • PEP-19
  • Pcp4l1

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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