Table 1.

Cm-PP16-1 Y63A, S66A, and S66D Mutants Are Dysfunctional in Their Capacity for Cell-to-Cell Trafficking

	Microinjection
	Movement (n [%])a
Injected Probe	Total	Extensive (10 to 20 Cells)	Limited (One Cell)	None (Injected Cell)
Lucifer yellow CH	18	18 (100)	0 (0)	0 (0)
F-dextranb	32	0 (0)	2 (6)	30 (94)
OG-labeled phloem-purified Cm-PP16-1c	46	44 (96)	2 (4)	0 (0)
Phloem-purified Cm-PP16-1 + F-dextran	41	37 (90)	2 (5)	2 (5)
His-Cm-PP16-1 + F-dextrand	33	31 (94)	2 (6)	0 (0)
His-Cm-PP16-1 S-all-A + F-dextran	40	0 (0)	10 (25)	30 (75)
His-Cm-PP16-1 S66A + F-dextran	40	0 (0)	8 (20)	32 (80)
His-Cm-PP16-1 S66D + F-dextran	41	0 (0)	13 (32)	28 (68)
His-Cm-PP16-1 Y63A + F-dextran	66	0 (0)	28 (42)	38 (58)
His-Cm-PP16-1 S12A + F-dextran	20	19 (95)	1 (5)	0 (0)

^aCell-to-cell movement of each fluorescent probe was analyzed 2 min after injection into an N. benthamiana mesophyll cell. A Leica confocal laser scanning microscope was used to record the extent of movement; this was categorized as extensive (probe spread out from the injected cell into 10 to 20 neighboring mesophyll cells), limited (probe moved into one neighboring cell), or none (probe remained in injected cell).

^b10-kD Dextran labeled with fluorescein isothiocyanate was used as a reporter for protein trafficking through plasmodesmata.

^cPhloem-purified Cm-PP16-1 was labeled with OG for direct analysis of protein trafficking.

^dRecombinant His-Cm-PP16-1 was expressed in and purified from E. coli.