Intestinal sugar transport

Table 1 Affinity constants of sugar transporters

Transporter	Km
SGLT1 (BBM)	Glucose:0.1-0.6 mmol/L
	(Wright et al, 2003)
GLUT2 (BLM)	Glucose:> 50 mmol/L
	Fructose: 66 mmol/L
	(Walmsley et al, 1998)
GLUT5 (BBM)	Fructose: 6-14 mmol/L
	(Walmsley et al, 1998)

Table 2 Inhibitors of sugar transporters

	Inhibitors
SGLT1	Phloridzin
GLUT2	Cytochalasin B
	Phloretin
GLUT5	Glyco-1, 3-oxazolidin-2- thiones, -ones (Girniene et al, 2003)
Na+K+-ATPase	Oubain

Table 3 Factors influencing transporter function

Factors influencing	Factors influencing	Factors influencing
SGLT1 function	GLUT2 function	GLUT5 function
Foxl1 (Katz et al, 2004)	PKCbII(Helliwell et al, 200b)	cAMP (Mahraoui et al, 1994)
AMPK (Walker et al, 2004)	p38(Helliwell et al, 200b)	p38 (Helliwell et al, 200b)
PKA (Wright et al, 1997)	ERK(Helliwell et al, 200b)	ERK (Helliwell et al, 200b)
PKC (Wright et al, 1997)	PI3K(Helliwell et al, 200b)	PI3K (Helliwell et al, 200b)
RS1 (Veyhl et al, 1993)	mTOR (Helliwell et al, 2003)	TNF-α (Garcia-Herrera, 2004)
HNF-1 (Martin et al, 2000)	AMPK (Walker et al, 2004)
Sp1 (Martin et al, 2000)
Hsp 70 (Ikari et al, 2002)
TGF-b (Ikari et al, 2002)