Isolation, characterization, and expression of cDNAs encoding murine alpha-mannosidase II, a Golgi enzyme that controls conversion of high mannose to complex N-glycans

The 3' end of Man II was found to be heterogeneous in length with the isolation ofthree distinct size classes of polyadenylated clones . The longest class of clones extends 2,543 by in the 3' direction from the end of the open reading frame before terminating in a poly(A) tract. Comparison between the longest aggregate clone sequence and the message size on Northern blots suggests that the predominant transcript likely reads through the region containing the three polyadenylation signals and uses a termination and polyadenylation signal an additional -1.4 kb further downstream. Repetitive element sequences were found in the long 3' untranslated region of both murine Man II and murine 51,4-galactosyltransferase (46) . Although this type of extended 3' untranslated region is common among the glycosyltransferases the functional significance of this extended transcript is not clear.