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Comparative Biochemistry and... May 2001Surfactant protein A (SP-A) is an abundant protein found in pulmonary surfactant which has been reported to have multiple functions. In this review, we focus on the... (Review)
Review
Surfactant protein A (SP-A) is an abundant protein found in pulmonary surfactant which has been reported to have multiple functions. In this review, we focus on the structural importance of each domain of SP-A in the functions of protein oligomerization, the structural organization of lipids and the surface-active properties of surfactant, with an emphasis on ultrastructural analyses. The N-terminal domain of SP-A is required for disulfide-dependent protein oligomerization, and for binding and aggregation of phospholipids, but there is no evidence that this domain directly interacts with lipid membranes. The collagen-like domain is important for the stability and oligomerization of SP-A. It also contributes shape and dimension to the molecule, and appears to determine membrane spacing in lipid aggregates such as common myelin and tubular myelin. The neck domain of SP-A is primarily involved in protein trimerization, which is critical for many protein functions, but it does not appear to be directly involved in lipid interactions. The globular C-terminal domain of SP-A clearly plays a central role in lipid binding, and in more complex functions such as the formation and/or stabilization of curved membranes. In recent work, we have determined that the maintenance of low surface tension of surfactant in the presence of serum protein inhibitors requires cooperative interactions between the C-terminal and N-terminal domains of the molecule. This effect of SP-A requires a high degree of oligomeric assembly of the protein, and may be mediated by the activity of the protein to alter the form or physical state of surfactant lipid aggregates.
Topics: Animals; Biopolymers; Lipids; Molecular Structure; Proteolipids; Pulmonary Surfactant-Associated Protein A; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants; Surface Tension
PubMed: 11369537
DOI: 10.1016/s1095-6433(01)00309-9 -
Archives of Biochemistry and Biophysics May 1980
Topics: Carrier Proteins; Cytoplasm; Dicyclohexylcarbodiimide; Mitochondria; Molecular Weight; Phosphates; Proteolipids; Saccharomyces cerevisiae; Solubility
PubMed: 6994653
DOI: 10.1016/0003-9861(80)90551-2 -
Mead Johnson Symposium on Perinatal and... 1987
Review
Topics: Animals; DNA; Gene Expression Regulation; Glycoproteins; Humans; Lung; Proteolipids; Pulmonary Surfactant-Associated Proteins; Pulmonary Surfactants; Structure-Activity Relationship
PubMed: 3332905
DOI: No ID Found -
Ukrainskii Biokhimicheskii Zhurnal... 1988N- and C-terminal amino acids of proteolipid proteins from the whole brain and some other organs were investigated. N-terminal amino acids were identified by the...
N- and C-terminal amino acids of proteolipid proteins from the whole brain and some other organs were investigated. N-terminal amino acids were identified by the dansylation procedure. C-terminal amino acids were determined after the enzymatic hydrolysis with carboxy peptidases A and B with the following dansylation. Phenyl alanine and lysine were identified as C-terminal amino acids of the proteolipids from the whole brain and only lysine--as the C-terminal amino acid of proteolipids from the heart, liver, kidney (cortical and medullary parts) and skeletal muscle. The corresponding N-terminal amino acids of the proteolipids from the whole brain were aspartic acid and glycine and of proteolipids from the heart, liver, kidney (cortical and medullary parts) and skeletal muscle--only aspartic acid. A comparison of the data obtained with the previous ones has shown that in the brain there exist only two types of proteolipids--one characteristic of myelin, another-- of mitochondria, and in other organs--only one characteristic of mitochondria.
Topics: Amino Acids; Animals; Brain Chemistry; Chromatography, Thin Layer; Kidney; Liver; Muscles; Myocardium; Organ Specificity; Proteolipids; Rats
PubMed: 3413844
DOI: No ID Found -
Journal of Neurochemistry Dec 1990In a developmental study, we have shown that DM-20 is present before proteolipid protein (PLP) in the fetal bovine cerebral hemispheres. When the white matter appears...
In a developmental study, we have shown that DM-20 is present before proteolipid protein (PLP) in the fetal bovine cerebral hemispheres. When the white matter appears (27-30 weeks of gestation), the amount of DM-20 drastically increases. DM-20 remains the major proteolipid until birth. PLP is detected only 2-4 weeks after the appearance of white matter, that is, more than 4 weeks after the appearance of DM-20. The early appearance of DM-20 at the beginning of myelination raises the question of its particular function. In the adult bovine cerebral hemispheres, PLP is the major proteolipid but DM-20 remains quantitatively important because the PLP/DM-20 ratio ranges from 1.5 to 1.7. In the same developmental study we have, in the fetal cerebral hemispheres, isolated and characterized a novel proteolipid (apparent Mr 20,000), which appears even before DM-20 and is not detected in the adult brain. It is structurally related to PLP and DM-20 because the first 31 N-terminal amino acid residues are the same. However, in immunoblot, it did not react either with the antitridecapeptide 117-129 antiserum of PLP or with the anti-C-terminal hexapeptide antiserum of PLP.
Topics: Animals; Brain; Cattle; Fetus; Myelin Proteins; Myelin Proteolipid Protein; Myelin Sheath; Proteolipids; Time Factors
PubMed: 1700073
DOI: 10.1111/j.1471-4159.1990.tb05798.x -
Journal of Chromatography Jan 1982Proteolipids from adult rat brain subcellular fractions were purified by a one-step procedure involving chromatography through Sephadex LH-60 eluted with an acidified...
Proteolipids from adult rat brain subcellular fractions were purified by a one-step procedure involving chromatography through Sephadex LH-60 eluted with an acidified chloroform-methanol mixture. The protein peak was eluted with the void volume and was free of adventitious lipids. The degree of purification was similar to that attained with the neutral-acidified chloroform-methanol dialysis method with the advantage that this new procedure can be carried out in only 3 h, with a recovery of proteins of 95-100%. Samples containing different lipid/protein ratios passed through the gel gave similar elution profiles. When labeled amino acids or palmitic acid were added to myelin total lipid extracts, no radioactivity was eluted with the protein, indicating that the proteolipid apoproteins purified by this method do not adsorb hydrophobic low-molecular-weight compounds.
Topics: Animals; Brain Chemistry; Cell Fractionation; Chromatography, Gel; Female; Male; Proteolipids; Rats; Rats, Inbred Strains
PubMed: 7056820
DOI: 10.1016/s0378-4347(00)80353-9 -
Biology of the Neonate Jun 1999Pulmonary surfactant protein B (SP-B) is a 79 amino acid peptide that is intimately associated with surfactant phospholipids in the alveolar airspace. Mutations of the... (Review)
Review
Pulmonary surfactant protein B (SP-B) is a 79 amino acid peptide that is intimately associated with surfactant phospholipids in the alveolar airspace. Mutations of the SP-B gene that result in complete absence of SP-B are invariably fatal in the neonatal period. The pathology associated with SP-B deficiency suggests that SP-B plays a critical role in integrating the synthesis, assembly and metabolism of the surfactant complex. A strategy is described to elucidate the role of SP-B in surfactant homeostasis by characterizing the pathophysiology associated with cell specific expression of SP-B constructs in vivo. Human SP-B constructs, under control of lung cell-specific promoters, were expressed in SP-B knockout mice in order to achieve expression of the human transgene in a null background. The effect of transgene expression on lung structure and function was assessed by biochemical, morphological and physiological analyses of the surfactant system in fetal and postnatal offspring.
Topics: Animals; Dimerization; Humans; Lung; Mice; Mice, Knockout; Mice, Transgenic; Mutagenesis; Proteolipids; Pulmonary Surfactants
PubMed: 10393388
DOI: 10.1159/000047041 -
Journal of Visualized Experiments : JoVE May 2013The electrophysiological method we present is based on a solid supported membrane (SSM) composed of an octadecanethiol layer chemisorbed on a gold coated sensor chip and...
The electrophysiological method we present is based on a solid supported membrane (SSM) composed of an octadecanethiol layer chemisorbed on a gold coated sensor chip and a phosphatidylcholine monolayer on top. This assembly is mounted into a cuvette system containing the reference electrode, a chlorinated silver wire. After adsorption of membrane fragments or proteoliposomes containing the membrane protein of interest, a fast solution exchange is used to induce the transport activity of the membrane protein. In the single solution exchange protocol two solutions, one non-activating and one activating solution, are needed. The flow is controlled by pressurized air and a valve and tubing system within a faraday cage. The kinetics of the electrogenic transport activity is obtained via capacitive coupling between the SSM and the proteoliposomes or membrane fragments. The method, therefore, yields only transient currents. The peak current represents the stationary transport activity. The time dependent transporter currents can be reconstructed by circuit analysis. This method is especially suited for prokaryotic transporters or eukaryotic transporters from intracellular membranes, which cannot be investigated by patch clamp or voltage clamp methods.
Topics: Adsorption; Electrophysiology; Gold; Membrane Proteins; Membranes, Artificial; Proteolipids; Sulfhydryl Compounds
PubMed: 23711952
DOI: 10.3791/50230 -
Frontiers in Bioscience (Landmark... Aug 2023Plasmolipin (PLLP) is a membrane protein located in lipid rafts that participates in the formation of myelin. It is also implicated in many pathologies, such as...
BACKGROUND
Plasmolipin (PLLP) is a membrane protein located in lipid rafts that participates in the formation of myelin. It is also implicated in many pathologies, such as neurological disorders, type 2 diabetes, and cancer metastasis. To better understand how PLLP interacts with raft components (gangliosides and cholesterol), we undertook a global study combining simulations and physicochemical measurements of molecular interactions in various PLLP-ganglioside systems.
METHODS
studies consisted of molecular dynamics simulations in reconstructed membrane environments. PLLP-ganglioside interaction measurements were performed by microtensiometry at the water-air interface on ganglioside monolayers.
RESULTS
We have elucidated the mode of interaction of PLLP with ganglioside GM1 and characterized this interaction at the molecular level. We showed that GM1 induces the structuring of the extracellular loops of PLLP and that this interaction propagates a conformational signal through the plasma membrane, involving a cholesterol molecule located between transmembrane domains. This conformational wave is finally transmitted to the intracellular domain of the protein, consistent with the role of PLLP in signal transduction.
CONCLUSIONS
This study is a typical example of the epigenetic dimension of protein structure, a concept developed by our team to describe the chaperone effect of gangliosides on disordered protein motifs which associate with lipid rafts. From a physiological point of view, these data shed light on the role of gangliosides in myelin formation. From a pathological point of view, this study will help to design innovative therapeutic strategies focused on ganglioside-PLLP interactions in various PLLP-associated diseases.
Topics: Humans; G(M1) Ganglioside; Gangliosides; Membrane Microdomains; Myelin Sheath; Proteolipids; Myelin and Lymphocyte-Associated Proteolipid Proteins
PubMed: 37664934
DOI: 10.31083/j.fbl2808157 -
Experimental Cell Research Nov 2009Oligodendrocytes (OLs), the myelin-producing cells of the central nervous system, segregate different surface subdomains at the plasma membrane as do other...
Oligodendrocytes (OLs), the myelin-producing cells of the central nervous system, segregate different surface subdomains at the plasma membrane as do other differentiated cells such as polarized epithelia and neurons. To generate the complex membrane system that characterizes myelinating OLs, large amounts of membrane proteins and lipids need to be synthesized and correctly targeted. In polarized epithelia, a considerable fraction of apical proteins are transported by an indirect pathway involving a detour to the basolateral membrane before being internalized and transported across the cell to the apical membrane by a process known as transcytosis. The apical recycling endosome (ARE) or its equivalent, the subapical compartment (SAC), of hepatocytes is an intracellular trafficking station involved in the transcytotic pathway. MAL2, an essential component of the machinery for basolateral-to-apical transcytosis, is an ARE/SAC resident protein. Here, we show that, after differentiation, murine oligodendrocyte precursor and human oligodendroglioma derived cell lines, Oli-neu and HOG, respectively, up-regulate the expression of MAL2 and accumulate it in an intracellular compartment, exhibiting a peri-centrosomal localization. In these oligodendrocytic cell lines, this compartment shares some of the main features of the ARE/SAC, such as colocalization with Rab11a, sensitivity to disruption of the microtubule cytoskeleton with nocodazole, and lack of internalized transferrin. Therefore, we suggest that the MAL2-positive compartment in oligodendrocytic cells could be a structure analogous to the ARE/SAC and might have an important role in the sorting of proteins and lipids for myelin assembly during oligodendrocyte differentiation.
Topics: Animals; Cell Differentiation; Cell Line; Cell Polarity; Humans; Membrane Proteins; Mice; Myelin Sheath; Myelin and Lymphocyte-Associated Proteolipid Proteins; Oligodendroglia; Oligodendroglioma; Protein Transport; Proteolipids; Up-Regulation; Vesicular Transport Proteins
PubMed: 19683524
DOI: 10.1016/j.yexcr.2009.08.003