Molecular identification and sequence analysis of Hillarin, a novel protein localized at the axon hillock

The monoclonal antibody Lan3-15 identifies a novel protein, Hillarin, that is localized to the axon hillock of leech neurons. Using this antibody we h ave identified a full length cDNA coding for leech Hillarin and determined its sequence. The gene encodes a 1274 residue protein with a predicted mole cular mass of 144013 Da. Data base searches revealed that leech Hillarin ha s potential orthologues in fly and nematode and that these proteins share t wo novel protein domains. The W180 domain is characterized by five conserve d tryptophans whereas the H domains share 21 invariant residues. In contras t to the arrangement in fly and nematode the cassette containing the W180 a nd H domains is repeated twice in leech Hillarin. This suggests that the le ech Hillarin sequence originated from a duplication event of an ancestral p rotein with single cassette structure. (C) 2001 Elsevier Science B.V. All r ights reserved.