Gene expression of Sh3d19, a novel adaptor protein with five Src homology 3 domains, in anagen mouse hair follicles.

Background: Sh3yl1, which contains one Src homology (SH) 3 domain, has been previously identified from mouse skin and considered to play an important role in hair follicle formation by interacting with other proteins.
Objective: We performed this study to identify proteins capable of associating with Sh3yl1.
Methods: We screened a mouse skin cDNA library using the SH3 domain of Sh3yl1 as bait in the yeast two-hybrid system.
Results: We identified a 420-amino acid-long protein containing a proline-rich stretch and five carboxyl-terminal SH3 domains, which we have termed Sh3d19. We confirmed the interactions between Sh3yl1 and Sh3d19 by in vitro binding assays. Northern blot analysis showed that Sh3d19 transcripts in mouse skin were expressed in accordance with the hair cycle. Furthermore, RNA in situ hybridization studies demonstrated that its transcripts were detected predominantly in the medulla cells at the level corresponding to the keratogenous zone of the hair follicles during the mid and late anagen phases.
Conclusion: Sh3d19 is a novel adaptor protein that may be involved in the development of medulla cells during the anagen phase.