Discovery of lipoprotein lipase pI isoforms and contributions to their characterization.
Lipoprotein lipase (LPL) plays a pivotal role in lipid metabolism and is implicated in several pathophysiological conditions. A large number of LPL studies have been performed in rat, although the amount of information derived from direct study of the protein in this species is limited. Here we attempted to examine possible modifications of LPL using proteomic tools. By combining high-resolution two-dimensional gel electrophoresis and Western blot with biological mass spectrometry we demonstrate the coexistence of multiple LPL pI isoforms in rat heart. We studied the origin of this pI heterogeneity by: (1) comparison with the 2D pattern of LPL from post-heparin rat plasma (as a source of mature LPL); (2) protein dephosphorylation; (3) protein deglycosylation; and (4) partial sequencing of LPL isoforms. The results reveal that LPL pI heterogeneity does not correspond to different stages of intracellular maturation or protein phosphorylation. It can be partially explained by glycosylation, although other post-translational modifications must also be involved. We also report the first partial sequence to be obtained from direct study of rat LPL protein. These findings should be the basis for further research aimed at identifying the molecular differences between LPL isoforms and exploring their potential functional implications.
Casanovas
Albert
A
Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
Carrascal
Montserrat
M
Abián
Joaquín
J
López-Tejero
M Dolores
MD
Llobera
Miquel
M
D000818:Animals; D002417:Cattle; D015180:Electrophoresis, Gel, Two-Dimensional; D006031:Glycosylation; D006493:Heparin / Q000737:chemistry; D006801:Humans; D050356:Lipid Metabolism; D008071:Lipoprotein Lipase / Q000737:chemistry*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D020033:Protein Isoforms; D011499:Protein Processing, Post-Translational; D040901:Proteomics / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar
D020033:Protein Isoforms; D006493:Heparin; D008071:Lipoprotein Lipase