Harp (harmonin-interacting, ankyrin repeat-containing protein), a novel protein that interacts with harmonin in epithelial tissues.
Mutations in the triple PDZ domain-containing protein harmonin have been identified as the cause of Usher deafness syndrome type 1C. Independently, we identified harmonin in a screen for genes expressed in pancreatic beta cells. Using a yeast two-hybrid assay, we show that the first PDZ domain of harmonin interacts with a novel protein, designated harp for harmonin-interacting, ankyrin repeat-containing protein. This interaction was confirmed in an over-expression system and in mammalian cells, and shown to be mediated by the three C-terminal amino acids of harp. Harp is expressed in many of the same epithelia as harmonin and co-localization of native harp and harmonin was demonstrated by confocal microscopy in pancreatic duct epithelium and in a pancreatic beta-cell line. Harp, predicted molecular mass 48 kDa, has a domain structure which includes three ankyrin repeats and a sterile alpha motif. Human harp maps to chromosome 16, and its mouse homologue to chromosome 7. Sequences with similarity to harp include the sans gene, mutations of which are responsible for deafness in the Jackson shaker 2 (js) mutant mouse and in human Usher syndrome type 1G. The functional domain structures of harp and harmonin, their interaction under native conditions and their co-localization suggest they constitute a scaffolding complex to facilitate signal transduction in epithelia.
Johnston
Anne M
AM
The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
Naselli
Gaetano
G
Niwa
Hideo
H
Brodnicki
Thomas
T
Harrison
Leonard C
LC
Góñez
L Jorge
LJ
D000595:Amino Acid Sequence; D000818:Animals; D017089:Ankyrin Repeat / Q000502:physiology*; D001483:Base Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002874:Chromosome Mapping; D003598:Cytoskeletal Proteins; D004848:Epithelium / Q000378:metabolism*; D020869:Gene Expression Profiling; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
C499675:ANKS4B protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C499676:Harp (harmonin-interacting) protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C477451:Sans protein, mouse; C492262:Ush1c protein, mouse