Brain CRMP Forms Heterotetramers Similar to Liver Dihydropyrimidinase

Abstract

The cytoplasmic collapsin response mediator protein CRMP62 is involved in the signaling cascade initiated by collapsin‐1, which collapses neuronal growth cones. To investigate the mechanism of CRMP action, we screened mouse and human fetal cDNA libraries by the yeast two‐hybrid method with CRMP as bait. Clones encoding CRMP1 and CRMP4 were isolated, suggesting that the CRMPs form multimers. This finding was confirmed by expressing various rat CRMP cDNAs in the yeast two‐hybrid system. Rat CRMP isoforms show differential association with one another. Heterooligomerization is preferred in both two‐hybrid and in vitro binding assays. Purified bovine brain CRMP migrates as a tetramer during size exclusion chromatography. Examination of binding with truncated forms of CRMPs indicates that the avid association of CRMPs requires nearly intact proteins. Through the analysis of CRMP chimeras, CRMP amino acids 8–134 and 281–435 are found to be essential for CRMP oligomerization. The tetrameric structure of CRMP resembles that of liver dihydropyrimidinase (DHPase), a protein that shares sequence similarity with the CRMPs. Although purified brain CRMP does not hydrolyze several DHPase substrates, it is likely that a related activity accounts for CRMP participation in neuronal growth cone signaling.

Isolation and Expression Pattern of Human Unc-33-Like Phosphoprotein 6/Collapsin Response Mediator Protein 5 (Ulip6/CRMP5): Coexistence with Ulip2/CRMP2 in Sema3A- Sensitive Oligodendrocytes

“…Our demonstration, by double labeling, of the coexpression of these two Ulip/CRMPs in a subpopulation of oligodendrocytes corroborates previous reports of specific interactions between Ulip/CRMP isoforms (Wang and Strittmatter, 1997;Fukada et al, 2000;Inatome et al, 2000). Expression of Ulip1/CRMP4 protein has also been described in adult brain oligodendrocytes (Nacher et al, 2000).…”

“…Several results support this hypothesis: (1) microtubules are present in oligodendrocytes and reflect oligodendrocyte function (Lunn et al, 1997), (2) Ulip2/CRMP2 mediates the dynamics of microtubules , and (3) protein kinase, which could phosphorylate the numerous phosphorylation sites of the Ulip/CRMPs, regulates oligodendrocyte process extension (Stariha et al, 1997) and can affect microtubule dynamics (Gotoh et al, 1991). Although these results show that oligodendrocytes are sensitive to Sema3A, other signals might also be mediated by Ulip/CRMPs (Wang and Strittmatter, 1997).…”

“…The presence of Ulip6/CRMP5 and/or Ulip2/CRMP2 mRNAs in some neurons in the absence of detectable protein indicates either rapid turnover of the protein or translational or posttranslational regulation of the protein. Phosphorylation, glycosylation, or association of Ulip6/CRMP5 and Ulip2/CRMP2 with other proteins (Bulliard et al, 1997;Wang and Strittmatter, 1997;Inatome et al, 2000) could limit the recognition of the protein by the antibodies.…”

TUC-4b, a Novel TUC Family Variant, Regulates Neurite Outgrowth and Associates with Vesicles in the Growth Cone

“…The members of this family have been identified previously as TOAD-64 (turned on after division, 64 kDa), Ulip (UNC-33 like protein), CRMP (collapsin response mediator protein), and DRP (dihydropyrimidinase related protein) (Table 1) (Quinn et al, 1999). Four isoforms (TUC-1 through TUC-4) that share 70 -80% amino acid identity currently comprise the TUC family (Wang and Strittmatter, 1997;Byk et al, 1998;Quinn et al, 1999). TUC-4 (Ulip-1) was identified as a protein that is regulated during neuronal differentiation in the cerebral cortex and in neuronal cell lines in response to NGF or retinoic acid (Minturn et al, 1995b;Byk et al, 1996;Gaetano et al, 1997).…”

Collapsin Response Mediator Proteins (CRMPs) Are a New Class of Microtubule-associated Protein (MAP) That Selectively Interacts with Assembled Microtubules via a Taxol-sensitive Binding Interaction

“…lacking enzymatic activity (1). CRMP2 was initially identified and cloned based on its up-regulation during neurogenesis (2,3) and discovered concurrently as an essential component of Sema3A signaling (2,3).…”