PRIMARY STRUCTURE OF THE NEURONAL CLATHRIN-ASSOCIATED PROTEIN AUXILINAND ITS EXPRESSION IN BACTERIA

The protein auxilin is a coat component of brain clathrin-coated vesic les. It interacts directly with the heavy chain of clathrin and suppor ts its assembly into regular cages [Ahle, S. and Ungewickell, E. (1990 ) J. Cell Biol. 111, 19-29]. The combined open reading frames of three cow brain cDNA clones with a total of 4531 nucleotides predict a mole cular mass of 99 504 Da for auxilin. The coding region is followed by a very long untranslated region of at least 1670 nucleotides. By North ern analysis, auxilin transcripts are found only in brain tissue. Auxi lin is not related to any of the previously sequenced clathrin-binding proteins, but the region of positions 50-350 is 29% identical (simila rity 56%) to the corresponding region of the actin-binding protein ten sin from chicken fibroblasts. Recombinant auxilin expressed in and pur ified from bacteria by affinity chromatography is functional with resp ect to clathrin binding.