This preclinical study suggests that lipoprotein lipase assembles into its active dimeric form in the endoplasmic reticulum prior to Golgi processing.
Does not change LPL-related clinical practice; hypothesis-generating for ER dimerization in human LPL maturation.
It has been suggested that lipoprotein lipase (LPL) can be assembled into its catalytically active dimeric form only after its oligosaccharide chains have been processed in the Golgi. To study this in a complete organ, LPL was metabolically labelled with [35S]methionine in perfused guinea-pigs hearts. After 10 min pulse-labelling, LPL protein was eluted as two peaks from heparin-agarose: peak 1 at about 0.65 M NaCl, peak 2 at about 0.95 M NaCl. Catalytic activity was associated only with peak 2. Model studies with bovine LPL showed that active dimeric LPL is eluted in peak 2, but after treatments that dissociate the enzyme into inactive monomers it is eluted in peak 1. Pulse-labelled LPL in both peak 1 and peak 2 was fully sensitive to treatment with endoglycosidase (Endo) H. With chase, peak 1 disappeared and peak 2 acquired resistance to Endo H. These findings suggest that core glycosylated LPL is assembled into dimers already in the endoplasmic reticulum and that processing of the oligosaccharide chains occurs after dimerization.
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Liu et al. (1993) studied this question.
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