Targeting of Slp4-a to WPBs depends on its Slp homology domain. (A) Cartoon overview of mCherry-tagged Slp4-a truncation variants, indicating the boundaries of the SHD domain. (B) Immunocytochemical analysis of intracellular localization of Slp4-a variants. HUVECs were transfected with mCherry-tagged constructs and fixed with paraformaldehyde 24 hours posttransfection. WPBs were visualized by immunostaining for VWF propeptide (green). Magnifications of boxed regions are shown on the right and the bottom. Arrowheads point to WPBs devoid of mCherry-Slp4-a-ΔSHD. Bars represent 10 μm.