Table 1.

Summary of the distribution of plasma membrane K⁺ membrane transport proteins and associated literature references.

Transport protein	Spatial distribution	Source
IRCs	DZ: epidermis, cortex, endodermis	Desbrosses et al., 2003
	UZ: epidermis	Lagarde et al., 1996
ORCs	DZ: epidermis, pericycle	Gaymard et al., 1998
		Ivashikina et al., 2001
K+/H+ symporters	DZ: epidermis, pericycle	Gierth et al., 2005

IRCs, inward rectifying channels; ORCs, outward rectifying channels; DZ, differentiation zone; UZ, undifferentiated zone.