DEVELOPMENTAL REGULATED GLYCOSYLATION OF DOPAMINE TRANSPORTER

The dopamine transporter (DAT) in rat striatum was examined during postnatal development and aging after photolabeling with [I-125]DEEP. The DAT-[I-125]DEEP protein complex from adult rats (2 months) appeared as a broad diffuse band in SDS-PAGE gels with average apparent molecular mass of about 80,000 Da as previously found. However, the molecular mass was lower at birth (day 0) and at postnatal ages 4 and 14 days. In aged rats (104 weeks), the molecular mass was slightly higher than that found in young adults (60 days). In binding experiments with [H-3]BTCP, there were age-related differences in K-d and B-max with decreases in both K-d and B-max found in aged rats. Treatment of photolabeled membranes with neuraminidase caused a reduction in DAT molecular mass, but age-related differences were maintained. Treatment with N-glycanase greatly reduced or eliminated the age-related differences. Several DAT peptide-specific polyclonal antibodies immunoprecipitated DAT[I-125]DEEP protein complex at different developmental ages. Taken together, these results suggest differential glycosylation of rat DAT occurs during postnatal development and aging; the increase is due to increases in the N-linked sugars rather than changes in either sialic acid content or the polypeptide.