Self-association of the plasma membrane-associated clathrin assembly protein AP-2

Kenneth A Beck, James H. Keen

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29 Scopus citations


A self-association reaction involving the plasma membrane-associated clathrin assembly protein AP-2 has been detected by incubating AP-2 alone under solution conditions that would favor the assembly of complete coat structures if clathrin were present. Self-association was rapid, unaffected by nonionic detergents, readily reversible, and gave rise to sedimentable aggregates. Only the AP subtype AP-2 exhibited self-association: the structurally or functionally related assembly proteins AP-1 and AP-3 and unrelated proteins neither self-associated nor were incorporated into the AP-2 aggregate. AP-2 interactions responsible for self-association were of high affinity, with an apparent Kd of approximately 10-8 M. By proteolytic dissection, the self-association domain was localized to the core of the molecule containing the intact 50- and 16-kDa polypeptides in association with the truncated 60-66-kDa moieties of the parent α/β polypeptides. Self-association of the intact AP-2 molecule was pH-dependent, exhibiting an apparent pKa ≈ 7.4. While it is unlikely that the large AP-2 aggregates formed in solution are themselves biologically relevant structures, the AP-2 interactions involved in their formation have properties consistent with their occurrence in intact cells and thus may be important in cellular functions of the plasma membrane-localized assembly protein.

Original languageEnglish (US)
Pages (from-to)4437-4441
Number of pages5
JournalJournal of Biological Chemistry
Issue number7
StatePublished - Mar 5 1991
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


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