P‐glycoproteins encoded by mdr 1b in murine gravid uterus and multidrug resistant tumor cell lines are differentially glycosylated

Abstract
There are 3 members of the multidrug-resitance gene family expressed in mouse. Only one of these, mdr lb, and its gene product P-glycoprotein are induced to high levels in the mouse endometrium during pregnancy. It is shown here that P-glycoprotein in the gravid uterus is significantly larger (M r 155000) compared to P-glycoprotein encoded by mdr lb in a murine multidrug-resistant cell line (M r 140000). However, both species co-migrate after enzymatic removal of N-linked sugars (M r 125000). These results demonstrate that differential glycosylation of the mdr lb gene product contributes to molecular heterogeneity found in P-glycoprotein from normal and multidrug-resistant cells.