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Genetic basis of familial interstitial lung disease: misfolding or function of surfactant protein C?American Journal of Respiratory and... May 2002
Topics: Animals; Humans; Lung Diseases, Interstitial; Mice; Mutation; Protein Folding; Proteolipids; Pulmonary Fibrosis; Pulmonary Surfactants
PubMed: 11991863
DOI: 10.1164/rccm.2203017 -
Molecular Membrane Biology 2002Studies of lipid-protein interactions in double-reconstituted systems involving both integral and peripheral or lipid-anchored proteins are reviewed. Membranes of... (Review)
Review
Studies of lipid-protein interactions in double-reconstituted systems involving both integral and peripheral or lipid-anchored proteins are reviewed. Membranes of dimyristoyl phosphatidylglycerol containing either myelin proteolipid protein or cytochrome c oxidase were studied. The partner peripheral proteins bound to these membranes were myelin basic protein or cytochrome c, respectively. In addition, the interactions between the myelin proteolipid protein and avidin that was membrane-anchored by binding to N-biotinyl phosphatidylethanolamine were studied in dimyristoyl phosphatidylcholine membranes. Steric exclusion plays a significant role when sizes of the peripheral protein and transmembrane domain of the integral protein are comparable. Even so, the effects on avidin-linked lipids are different from those induced by myelin basic protein on freely diffusible lipids, both interacting with the myelin proteolipid protein. Both the former and the cytochrome c/cytochrome oxidase couple evidence a propagation of lipid perturbation out from the intramembrane protein interface that could be a basis for formation of microdomains.
Topics: Animals; Avidin; Biotin; Cattle; Cytochrome c Group; Electron Transport Complex IV; Horses; Humans; Lipid Metabolism; Membrane Proteins; Myelin Basic Protein; Myelin Proteolipid Protein; Protein Binding; Proteolipids
PubMed: 12512771
DOI: 10.1080/09687680210162419 -
Immunological Reviews Feb 2000Research over the last decade on the surfactant proteins SP-A and SP-D suggests roles beyond surfactant lipid homeostasis, involving their participation in innate immune... (Review)
Review
Research over the last decade on the surfactant proteins SP-A and SP-D suggests roles beyond surfactant lipid homeostasis, involving their participation in innate immune defence. SP-A and SP-D bind and agglutinate an impressive array of non-self structures, ranging from bacteria and fungi to allergens and environmental inorganic substrates. Complementing binding. SP-A and SP-D initiate and enhance immune cell ingestion and killing of targets. Recently, some exciting developments have extended and clarified their contributions to innate immunity. Knockout mice for SP-A and SP-D have been developed. The SP-A knockout confirms that SP-A plays a key role in defence against lung pathogens and reveals the underlying defense mechanisms that require SP-A. These surfactant proteins have also been shown to have important roles in modulating the immune response, instructing, yet quenching, the immune reactions in the lung. The crystal structure of SP-D plus functional studies with recombinantly altered forms of SP-A and SP-D has begun to characterise the structural motifs responsible for mediating their immune functions. Linkage and polymorphism analysis is explaining the role these genes may play in lung diseases and infection.
Topics: Binding Sites; Glycoproteins; Humans; Lectins; Lung; Models, Molecular; Protein Binding; Proteolipids; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactant-Associated Protein D; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants
PubMed: 10719668
DOI: 10.1034/j.1600-065x.2000.917308.x -
Molecular Medicine Reports Apr 2024The myelin and lymphocyte protein (MAL) family is a novel gene family first identified and characterized in 2002. This family is comprised of seven members, including... (Review)
Review
The myelin and lymphocyte protein (MAL) family is a novel gene family first identified and characterized in 2002. This family is comprised of seven members, including MAL, MAL2, plasmolipin, MALL, myeloid differentiation‑associated marker (MYADM), MYADML2 and CMTM8, which are located on different chromosomes. In addition to exhibiting extensive activity during transcytosis, the MAL family plays a vital role in the neurological, digestive, respiratory, genitourinary and other physiological systems. Furthermore, the intimate association between MAL and the pathogenesis, progression and metastasis of malignancies, attributable to several mechanisms such as DNA methylation has also been elucidated. In the present review, an overview of the structural and functional properties of the MAL family and the latest research findings regarding the relationship between several MAL members and various cancers is provided. Furthermore, the potential clinical and scientific significance of MAL is discussed and directions for future research are summarized.
Topics: Humans; Myelin and Lymphocyte-Associated Proteolipid Proteins; Proteolipids; Myelin Proteins; Proteins; Neoplasms; Cell Transformation, Neoplastic; Carcinogenesis; Lymphocytes; Chemokines; MARVEL Domain-Containing Proteins
PubMed: 38362940
DOI: 10.3892/mmr.2024.13181 -
The Journal of Membrane Biology 1981Proteolipids extracted from bovine kidney plasma membrane induce irreversible changes in the electrical properties of lipid bilayers formed from diphytanoyl...
Proteolipids extracted from bovine kidney plasma membrane induce irreversible changes in the electrical properties of lipid bilayers formed from diphytanoyl phosphatidylcholine. The interaction with the proteolipid produces channels which are cation selective. At low protein concentrations (i.e., less than 0.6 microgram/ml), the single-channel conductance is approximately 10 pS in 100 mM KCl and 3 pS in 100 mM NaCl. In the presence of protein concentrations above 1 microgram/ml, another population of channels appears. These channels have a conductance of about 100 pS in 100 mM KCl and 30 pS in 100 mM NaCl. Further, these channels are voltage dependent in KCl, closing when the voltage is clamped at values greater than or equal to 30 mV. The steady-state membrane conductance, measured at low voltages, was found to increase proportional to a high power (2-3) of the proteolipid concentration present in one of the aqueous phases. In 100 mM NaCl, the conductance increases at protein concentrations above 5 microgram/ml, whereas in 100 mM KCl it increases at protein concentrations above 0.6 microgram/ml. These measurements indicate that the higher steady-state conductance observed in KCl at a given proteolipid concentration in a multi-channel membrane presumably results because more channel incorporate in the presence of KCl than in the presence of NaCl. The two major fractions which comprise the proteolipid complex were also tested on bilayers. It was found that both fractions are required to produce the effects described.
Topics: Animals; Cattle; Cell Membrane; Electric Conductivity; Ion Channels; Kidney; Lipid Bilayers; Membrane Potentials; Membrane Proteins; Proteolipids
PubMed: 6273572
DOI: 10.1007/BF01969448 -
Genes To Cells : Devoted To Molecular &... Jun 2003The vacuolar-type proton-translocating adenosine triphosphatase (V-ATPase) plays important roles in cell growth and tumour progression. V-ATPase is composed of two...
BACKGROUND
The vacuolar-type proton-translocating adenosine triphosphatase (V-ATPase) plays important roles in cell growth and tumour progression. V-ATPase is composed of two distinct structures, a hydrophilic catalytic cytosolic sector (V(1)) and a hydrophobic transmembrane sector (V(0)). The V(1) sector is composed of 5-8 different subunits with the structure A(3)B(3)C(1)D(1)E(1)F(1)G(1)H(1). The V0 sector is composed of 5 different subunits with the structure 1161381191166. The over-expression of 16-kDa proteolipid subunit of V-ATPase in the perinuclear region of the human adventitial fibroblasts promotes phenotypic modulation that contributes to neointimal formation and medial thickening. A relationship between oncogenicity and the expression of the 16-kDa proteolipid has also been suggested in human pancreatic carcinoma tissue.
RESULTS
We found that the mRNA levels of the 16-kDa proteolipid but not of the 70-kDa subunit of V-ATPase in human myofibroblasts were more abundant in serum-containing medium (MF(+) cells) than serum-free medium (MF(-) cells). In HeLa cells, the levels of mRNA and protein of the 16-kDa, 21-kDa or 70-kDa were clearly suppressed when the corresponding anti-sense oligonucleotides were administered to the culture medium. The growth rate and viability (mostly due to necrosis) of HeLa cells were reduced markedly by the 16-kDa and 21-kDa anti-sense, but little by the 70-kDa anti-sense, and not at all by any sense oligonucleotides. The localization of 16-kDa/21-kDa proteolipid subunits was different from that of the 70-kDa subunit in HeLa cells.
CONCLUSION
These results suggest that the 16-kDa and 21-kDa proteolipid subunits of the V0 sector play crucial roles in growth and death of cultured human cells. Our results may provide new insights into the mechanism and therapeutic implications for vessel wall hyperplasia and tumorigenesis.
Topics: Cell Death; Cell Division; Fibroblasts; HeLa Cells; Humans; Isoenzymes; Muscle, Smooth, Vascular; Necrosis; Oligonucleotides, Antisense; Proteolipids; RNA, Messenger; Saphenous Vein; Vacuolar Proton-Translocating ATPases
PubMed: 12786941
DOI: 10.1046/j.1365-2443.2003.00651.x -
EXS 2000Lipophilic peptides and proteins present specific problems during preparation and analysis which require the use of modified methodology. This chapter discusses some of... (Review)
Review
Lipophilic peptides and proteins present specific problems during preparation and analysis which require the use of modified methodology. This chapter discusses some of the methods that have been employed in the isolation and structural studies of the pulmonary surfactant-associated proteins B and C (SP-B and SP-C), other proteins with lipid-like physicochemical properties, and the SP-B precursor. In particular, methods for separation and analysis of peptide/lipid mixtures, high-resolution separation of lipopeptides, analysis of fatty acylated peptides, and secondary and tertiary structure analysis of lipopeptides are discussed.
Topics: Acylation; Amino Acid Sequence; Chromatography, High Pressure Liquid; Lipoproteins; Mass Spectrometry; Molecular Sequence Data; Peptides; Proteolipids; Pulmonary Surfactants
PubMed: 10803379
DOI: 10.1007/978-3-0348-8458-7_12 -
The American Journal of Physiology Aug 1992Traditionally, our thinking about surfactant proteins has centered around their effects on the biophysical properties of surfactant phospholipids. It is now apparent... (Review)
Review
Traditionally, our thinking about surfactant proteins has centered around their effects on the biophysical properties of surfactant phospholipids. It is now apparent that the three major surfactant proteins (SP-A, SP-B, and SP-C) are a biochemically and functionally diverse group of mammalian peptides. Accumulated data suggest that they have roles beyond modulation of alveolar surface tension. SP-C is a 33-35 amino acid peptide found in organic extracts of pulmonary surfactant. In part, because of its extreme hydrophobicity, a full understanding of SP-C is presently incomplete. Progress to date has included evaluation of the biophysical properties and investigations of the SP-C gene, including studies of the SP-C promoter. This review describes the unique structural and functional properties of the SP-C molecule and summarizes available data on its molecular biology and metabolism. Studies from literature show that SP-C represents a physiologically important peptide with novel structural properties; namely, extreme hydrophobicity, an alpha-helical membrane spanning region, and a unique posttranslational modification: palmitoylation. From data on similarly modified proteins, we propose that the properties of SP-C, including the covalent addition of palmitic acid, render it capable of being targeted to and interacting with specific cell membranes. A complete understanding of SP-C, especially with regard to its metabolism and function, may require a reorientation of our thinking to consider SP-C as a membrane peptide and not just as a "surfactant protein."
Topics: Amino Acid Sequence; Animals; Genes; Humans; Molecular Sequence Data; Protein Processing, Post-Translational; Proteolipids; Pulmonary Surfactants
PubMed: 1514639
DOI: 10.1152/ajplung.1992.263.2.L151 -
Cellular and Molecular Life Sciences :... Apr 2022Proteolipids are proteins with unusual lipid-like properties. It has long been established that PLP and plasmolipin, which are two unrelated membrane-tetra-spanning...
Proteolipids are proteins with unusual lipid-like properties. It has long been established that PLP and plasmolipin, which are two unrelated membrane-tetra-spanning myelin proteolipids, can be converted in vitro into a water-soluble form with a distinct conformation, raising the question of whether these, or other similar proteolipids, can adopt two different conformations in the cell to adapt their structure to distinct environments. Here, we show that MALL, another proteolipid with a membrane-tetra-spanning structure, distributes in membranes outside the nucleus and, within the nucleus, in membrane-less, liquid-like PML body biomolecular condensates. Detection of MALL in one or other environment was strictly dependent on the method of cell fixation used, suggesting that MALL adopts different conformations depending on its physical environment -lipidic or aqueous- in the cell. The acquisition of the condensate-compatible conformation requires PML expression. Excess MALL perturbed the distribution of the inner nuclear membrane proteins emerin and LAP2β, and that of the DNA-binding protein BAF, leading to the formation of aberrant nuclei. This effect, which is consistent with studies identifying overexpressed MALL as an unfavorable prognostic factor in cancer, could contribute to cell malignancy. Our study establishes a link between proteolipids, membranes and biomolecular condensates, with potential biomedical implications.
Topics: Biomolecular Condensates; Cell Nucleus; Humans; Molecular Conformation; Neoplasms; Proteolipids
PubMed: 35399121
DOI: 10.1007/s00018-022-04270-w -
Biochemical Society Transactions Feb 1994
Review
Topics: Animals; Chemotaxis; Glycoproteins; Humans; Macromolecular Substances; Macrophages; Macrophages, Alveolar; Phagocytosis; Proteolipids; Pulmonary Surfactant-Associated Protein D; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants
PubMed: 8206199
DOI: 10.1042/bst0220100