Previously we described the localization and gender differences (GD) of the high affinity SGLT1 (Slc5a1) in rat kidney (K) and small intestine (SI) using an affinity purified antibody (Ab) for the rat SGLT1-specific peptide (rSGLT1-Ab), which, however, cross-reacted with a 40 kDa polypeptide in Western blots (WB) (Sabolic et al., Am J Physiol Renal Physiol 290:913-926, 2006). Using a shortened peptide for immunization, we generated an improved, more specific rSGLT1-Ab. In WB of isolated brush-border membranes from rat K and SI, the Ab labeled a single protein band of ~75 kDa. The K expression of rSGLT1 protein was correlated with the expression of rSGLT1 mRNA in RT-PCR studies. In K of adult male (M) and female (F) rats, WB and RT-PCR data, and immunolocalization data in tissue cryosections (IC) revealed: 1) major localization of rSGLT1 protein in the proximal tubule (PT) S2 (weakly) and S3 segments (strongly), 2) GD in both tissue zones (M

Fundamental medical sciences