Axon Bound

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Science  13 Sep 2013:
Vol. 341, Issue 6151, pp. 1153
DOI: 10.1126/science.341.6151.1153-d

Developing mammalian neurons extend multiple neurites, one of which goes on to form the mature axon. Parker et al. have identified distinct and opposite roles for two isoforms of atypical protein kinase C (aPKC). In mammals, the gene Prkcl encodes aPKC-λ whereas the gene Prkcz encodes aPKC-ζ along with a truncated enzyme PKM-ζ, which lacks the N terminus of aPKC-ζ. In embryonic rat hippocampal neurons, aPKC-ζ was present at the tip of the neurite destined to become the axon, where it associated with polarity complex proteins Par3 and Par6. At the other neurites, Par3 was bound to PKM-ζ, which competed with aPKC-λ for binding to Par3 and inhibited, rather than promoted, axon formation. Thus, competition for binding of the two isoforms, which is then stabilized by feedback, may underlie the symmetry-breaking process that yields the typical neuronal morphology of a long axon and multiple dendrites.

Proc. Natl. Acad. Sci. U.S.A. 110, 14450 (2013).

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