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Results for “Phosphoserine”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Microgravity alters protein phosphorylation changes during initiation of sea urchin sperm motility

European Space Agency (ESA) studies demonstrated that bull sperm swim with higher velocity in microgravity (microG) than at 1 G. Coupling between protein phosphorylation and sperm motility during activation in microG and at 1 G was examined in the ESA Biorack on two space shuttle missions. Immotile sperm were activated to swim (86-90% motility) at launch +20 h by dilution into artificial seawater (ASW). Parallel ground controls were performed 2 h after the flight experiment. Activation after 0, 30, and 60 s was terminated with electrophoresis sample buffer and samples analyzed for phosphoamino acids by Western blotting. Phosphorylation of a 130-kDa phosphothreonine-containing protein (FP130) occurred three to four times faster in microG than at 1 G. A 32-kDa phosphoserine-containing protein was significantly stimulated at 30 s but returned to 1 G control levels at 60 s. The rate of FP130 phosphorylation in microG was attenuated by D2O, suggesting that changes in water properties participate in altering signal transduction. Changes in FP130 phosphorylation triggered by the egg peptide speract were delayed in microG. These results demonstrate that previously observed effects of microG on sperm motility are coupled to changes in phosphorylation of specific flagellar proteins and that early events of sperm activation and fertilization are altered in microG.

NASA Experiment Number 9403057 2/2↗
NASA NTRS1998

Identification of phosphoproteins coupled to initiation of motility in live epididymal mouse sperm

A method for collecting live immotile cauda epididymal mouse sperm that initiate motility by dilution into an activation buffer is described. Sperm in collection buffer showed low percent motility (MOT) and population progression (PRG) that increased 10-fold and 9-fold, respectively, during the first 2 min after dilution into activation buffer. Western phosphoserine (pS), phosphothreonine (pT), and phosphotyrosine (pY) analysis revealed a 120 kDa protein that markedly increased in pT content during initiation of motility and may be related to FP130, the motility-coupled axonemal protein of sea urchin sperm. A prominent 82 kDa protein that was pS and pT-phosphorylated in immotile and motile sperm is likely the fibrous sheath component AKAP82 that is phosphorylated during spermatogenesis. Analysis of live human sperm also identified a prominent 120 kDa pT protein. Thus it appears that phosphorylation of FP130 and related 120 kDa proteins in mouse, and perhaps human sperm, represent common targets during motility initiation in sperm. Copyright 1998 Academic Press.

Non-NASA Center↗
NASA NTRS1995

EDTA-insoluble, calcium-binding proteoglycan in bovine bone

A calcium ion precipitable, trypsin-generated proteoglycan fragment has been isolated from the demineralized, EDTA-insoluble matrices of bone. The demineralized matrix was completely digested with trypsin, increasing concentrations of CaCl2 were added to the supernatant, and the resulting precipitates were analyzed. The amount of precipitate gradually increased with higher concentrations of calcium and was reversibly solubilized by EDTA. After molecular sieve and anion exchange chromatography, a proteoglycan-containing peak was obtained. Immunochemical analysis showed that this peak contained chondroitin 4-sulfate and possibly keratan sulfate. Amino acid analysis showed that this proteoglycan contained high amounts of aspartic acid/asparagine (Asx), serine (Ser), glutamic acid/glutamine (Glx), proline (Pro), and glycine (Gly); however, it contained little leucine (Leu) which suggests that it is not a member of the leucine-rich small proteoglycan family. In addition, significant amounts of phosphoserine (P-Ser) and hydroxyproline (Hyp) were identified in hydrolysates of this fraction. A single band (M(r) 59 kDa) was obtained on SDS-PAGE that stained with Stains-all but not with Coomassie Brilliant Blue R-250. If bone powder was trypsinized prior to demineralization, this proteoglycan-containing fraction was not liberated. Collectively, these results indicate that a proteoglycan occurs in the demineralized matrix that is precipitated with CaCl2 and is closely associated with both mineral and collagen matrices. Such a molecule might facilitate the structural network for the induction of mineralization in bone.

NASA Program Space Physiology and Countermeasures↗
NASA NTRS1993

Phosphate cycling on the basic protein of Plodia interpunctella granulosis virus

The presence of infected cell-specific phosphoproteins was investigated in Plodia interpunctella granulosis virus (PiGV)-infected fat body using [32P]orthophosphoric acid labeling. One infected cell-specific phosphoprotein had a mobility similar to that of the basic protein (VP12) of PiGV. Further analysis, using immunoblotting and acid-urea gel analysis of infected fat body, confirmed that this phosphoprotein was VP12. However we did not detect phosphorylated VP12 in 32P-labeled nucleocapsids. Phosphoamino acid analysis of 32P-labeled VP12 revealed that phosphoserine was present in the basic protein. Since VP12 is phosphorylated in the infected cell, but not in the nucleocapsid, it appears that dephosphorylation of VP12 is a critical event in the life cycle of the virus. We therefore assayed virus nucleocapsids and infected fat body for the presence of phosphatase activity. Phosphatase activity was not detected in the virus, but the infected fat body had more activity than uninfected fat body. A model for nucleocapsid assembly and uncoating is presented which takes into account the phosphorylation state of VP12, the role of Zn2+ in the nucleocapsid, and the role of the capsid-associated kinase.

NASA Discipline Cell Biology↗
NASA NTRS1992

Phosphorylation of the budgerigar fledgling disease virus major capsid protein VP1

The structural proteins of the budgerigar fledgling disease virus, the first known nonmammalian polyomavirus, were analyzed by isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The major capsid protein VP1 was found to be composed of at least five distinct species having isoelectric points ranging from pH 6.45 to 5.85. By analogy with the murine polyomavirus, these species apparently result from different modifications of an initial translation product. Primary chicken embryo cells were infected in the presence of 32Pi to determine whether the virus structural proteins were modified by phosphorylation. SDS-PAGE of the purified virus structural proteins demonstrated that VP1 (along with both minor capsid proteins) was phosphorylated. Two-dimensional analysis of the radiolabeled virus showed phosphorylation of only the two most acidic isoelectric species of VP1, indicating that this posttranslational modification contributes to VP1 species heterogeneity. Phosphoamino acid analysis of 32P-labeled VP1 revealed that phosphoserine is the only phosphoamino acid present in the VP1 protein.

Non-NASA Center↗