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Keywords:

  • adaptor protein complexes;
  • AP-1;
  • clathrin;
  • trans-Golgi network;
  • membrane traffic;
  • zebrafish;
  • gut

Abstract

Protein transport between the trans-Golgi network and endosomes is mediated by transport vesicles formed by the adaptor-protein complex AP-1, consisting of the adaptins γ1, β1, μ1, σ1. Mammalia express μ1A ubiquitously and isoform μ1B in polarized epithelia. Mouse γ1 or μ1A 'knock out's revealed that AP-1 is indispensable for embryonic development. We isolated μ1A and μ1B from Danio rerio. Analysis of μ1A and μ1B expression revealed tissue-specific expression for either one during embryogenesis and in adult tissues in contrast to their expression in mammalia. μ1B transcript was detected in organs of endodermal derivation and “knock-down” experiments gave rise to embryos defective in formation of intestine, liver, and pronephric ducts. Development ceased at 7–8 dpf. μ1B is not expressed in murine liver, indicating loss of μ1B expression and establishment of alternative sorting mechanisms during mammalian development. Developmental Dynamics 239:2404–2412, 2010. © 2010 Wiley-Liss, Inc.