Ensures, when in complex with COG2 and FPP2/VETH2, the correct secondary cell wall (SCW) deposition pattern by recruiting exocyst components to cortical microtubules in xylem cells during secondary cell wall deposition by recruiting EXO70A1. Interacts with WPP/MAF proteins (By similarity). Binds to COG2; this interaction promotes the association between cortical microtubules and EXO70A1 (PubMed:25541219). Present in vesicle-like small compartments which exhibit microtubule plus-end-directed and end-tracking dynamics. Accumulates in preferentially xylem cells. Belongs to the FPP family.