title: Oligomeric protein complexes of apolipoproteins stabilize the internal fluid environment of organism in redfins of the Tribolodon genus [Pisces; Cypriniformes, Cyprinidae].
abstract: One of the most important functions of plasma proteins in vertebrates is their participation in osmotic homeostasis in the organism. Modern concepts about plasma proteins and their capillary filtration are based on a model of large monomeric proteins that are able to penetrate the interstitial space. At the same time, it was revealed that a considerable amount of oligomeric complexes are present in the low-molecular-weight (LM) protein fraction in the extracellular fluids of fishes. The functions of these complexes are unknown. In the present study, we investigated the LM-fraction proteins in the plasma and interstitial fluid (IF) of redfins of the genus Tribolodon. This fish alternatively spends parts of its life cycle in saline and fresh waters. We identified the protein Wap65, serpins and apolipoproteins in this fraction. By combining the methods of 2D-E under native and denaturing conditions with MALDI, we demonstrated that only apolipoproteins formed complexes. We showed that serum apolipoproteins (АроА-I, Аро-14) were present in the form of homooligomeric complexes that were dissociated with the release of monomeric forms of proteins in the course of capillary filtration to IF. Dissociation of homooligomers is not directly correlated with the change in salinity but is correlated with seasonal dynamics. We found that there was a significant decrease in the total protein concentration in IF relative to plasma. Therefore, we suggested that dissociation of homooligomeric complexes from various apolipoproteins supports the isoosmoticity of extracellular fluids relative to capillary wall stabilization through a fluid medium in fish.
authors.affiliation: Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, 152742, Nekouzskii raion, Yaroslavl oblast, Russia. Electronic address: aam@ibiw.yaroslavl.ru.
authors.forename: Alla M
authors.initials: AM
authors.lastname: Andreeva
authors.affiliation: Lomonosov Moscow State University, A. N. Belozersky Institute of Physico-Chemical Biology, Moscow 119992, Leninskye gory, house 1, building 40, Russia.
authors.forename: Marina V
authors.initials: MV
authors.lastname: Serebryakova
authors.affiliation: Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, 152742, Nekouzskii raion, Yaroslavl oblast, Russia; A.V. Zhirmunsky Institute of Marine Biology, National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia.
authors.forename: Nina E
authors.initials: NE
authors.lastname: Lamash
mesh_terms: D000818:Animals; D001053:Apolipoproteins / Q000737:chemistry* / Q000378:metabolism*; D003530:Cyprinidae / Q000378:metabolism*; D004777:Environment; D045604:Extracellular Fluid / Q000737:chemistry* / Q000378:metabolism*; D008970:Molecular Weight; D055503:Protein Multimerization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001053:Apolipoproteins
keywords: Cyprinidae; Plasma and interstitial fluid proteins; Proteomics; Redfins