scholarly journals Structure and function of rat liver polysome populations. I. Complexity, frequency distribution, and degree of uniqueness of free and membrane-bound polysomal polyadenylate-containing RNA populations.

1981 ◽  
Vol 90 (2) ◽  
pp. 495-506 ◽  
Author(s):  
M M Mueckler ◽  
H C Pitot
Keyword(s):  
Frequency Distribution ◽  
Rat Liver ◽  
Structure And Function ◽  
High Salt ◽  
Cross Contamination ◽  
Membrane Bound ◽  
High Yields ◽  
And Function

Free and membrane-bound polysomes were isolated from rat liver in high yields with minimal degradation, cross-contamination, or contamination by nuclear or nonpolysomal cytoplasmic ribonucleoprotein. Poly(A)+ RNA fractions isolated from free and bound polysomal RNA (poly(A)+ RNAfree and poly(A)+ RNAbound) by oligo(dT) cellulose chromatography exhibited number-average lengths of 1,600 and 1,200 nucleotides, respectively, on formamide sucrose gradients. Poly(A)+ RNAfree and poly(A)+ RNAbound contain 9.1 +/- 0.55 and 10.7 +/- 0.50% poly(A) as measured by hybridization to [3H]poly(U) and comprise 2.37 and 1.22% of their respective polysomal RNA populations. Homologous poly(A)+ RNA-cDNA hybridizations revealed that greater than 95% of the mass of poly(A)+ RNAfree and poly(A)+ RNAbound contain nucleotide complexities of about 3.4 x 10(7) and 6.0 x 10(6), respectively. This represents about 20,000 and 5,000 poly(A)+ RNA species of average sizes. Heterologous hybridizations suggested that considerable overlap exists between poly(A)+ RNAfree and poly(A)+ RNAbound sequences that cannot be attributed to cross-contamination. This was confirmed by conducting heterologous reactions using kinetically enriched cDNA populations. Heterologous hybridizations involving poly(A)+ RNA derived from tightly bound polysomes and cDNAfree indicated tha most of the overlapping sequences are not contributed by loosely bound (high-salt releasable) polysomes. The ramifications of these findings are discussed.

scholarly journals Differences in size, structure and function of free and membrane-bound polyribosomes of rat liver. Evidence for a single class of membrane-bound polyribosomes

1977 ◽  
Vol 168 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J C Ramsey ◽  
W J Steele
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Size Structure ◽  
Large Fraction ◽  
Liver Homogenate ◽  
Structure And Function ◽  
Structural And Functional Properties ◽  
Membrane Bound ◽  
And Function

Free loosely bound and tightly bound polyribosomes were separated from rat liver homogenate by salt extraction followed by differential centrifugation, and several of their structural and functional properties were compared to resolve the existence of loosely bound polyribosomes and verify the specificity of the separation. The free and loosely bound polyribosomes have similar sedimentation profiles and polyribosome contents, their subunit proteins have similar electrophoretic patterns and their products of protein synthesis in vitro show a close correspondence in size and amounts synthesized. In contrast, the tightly bound polyribosomes have different properties from those of the free and loosely bound polyribosomes; their average size is significantly smaller; their polyribosome content is higher; their 60 S-subunit proteins lack two components and contain four or more components not found elsewhere; their products of protein synthesis in vitro differ in size and amounts synthesized. These observations show that rat liver membranes entrap a large fraction of the free polyribosomes at low salt concentrations and that these polyribosomes are similar to those of the free-polyribosome fraction and are different from those of the tightly bound polyribosome fraction in size, structure and function.

Effects of Alkyl Alcohols and Related Chemicals on Rat Liver Structure and Function

1991 ◽  
Vol 41 (6) ◽  
pp. 405-413
Author(s):  
Takashi Wakabayashi ◽  
Kayo Adachi ◽  
Jerzy Popinigis
Keyword(s):  
Rat Liver ◽  
Structure And Function ◽  
Liver Structure ◽  
And Function

scholarly journals Structure and function of a malaria transmission blocking vaccine targeting Pfs230 and Pfs230-Pfs48/45 proteins

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Kavita Singh ◽  
Martin Burkhardt ◽  
Sofia Nakuchima ◽  
Raul Herrera ◽  
Olga Muratova ◽  
...  
Keyword(s):  
Membrane Surface ◽  
Structure And Function ◽  
Fab Fragment ◽  
Membrane Anchor ◽  
Transmission Blocking ◽  
Vaccine Candidates ◽  
Membrane Bound ◽  
And Function ◽  
Transmission Blocking Vaccine

AbstractProteins Pfs230 and Pfs48/45 are Plasmodium falciparum transmission-blocking (TB) vaccine candidates that form a membrane-bound protein complex on gametes. The biological role of Pfs230 or the Pfs230-Pfs48/45 complex remains poorly understood. Here, we present the crystal structure of recombinant Pfs230 domain 1 (Pfs230D1M), a 6-cysteine domain, in complex with the Fab fragment of a TB monoclonal antibody (mAb) 4F12. We observed the arrangement of Pfs230 on the surface of macrogametes differed from that on microgametes, and that Pfs230, with no known membrane anchor, may exist on the membrane surface in the absence of Pfs48/45. 4F12 appears to sterically interfere with Pfs230 function. Combining mAbs against different epitopes of Pfs230D1 or of Pfs230D1 and Pfs48/45, significantly increased TB activity. These studies elucidate a mechanism of action of the Pfs230D1 vaccine, model the functional activity induced by a polyclonal antibody response and support the development of TB vaccines targeting Pfs230D1 and Pfs230D1-Pfs48/45.

9-Aminoacridine Binding to Chloroplast Membranes in Dark. Reversal by Mg2+

1978 ◽  
Vol 33 (1-2) ◽  
pp. 108-112 ◽  
Author(s):  
Salil Bose ◽  
George E. Hodi
Keyword(s):  
Thylakoid Membranes ◽  
Fluorescence Yield ◽  
Structure And Function ◽  
Chloroplast Membranes ◽  
Chemical Binding ◽  
Apparent Binding Constant ◽  
Low Salt ◽  
Membrane Bound ◽  
And Function ◽  
Function Interpretation

Abstract 9-Aminoacridine (9AA) binds to photosynthetic m em branes of unilluminated chloroplasts in low-salt media. The binding was insensitive to the uncouplers of photophosphorylation. The apparent binding constant was 140 μM . The binding isotherm as a function of 9AA concentration was sigmoid, and approximately 3 mol 9AA/mol chlorophyll was bound at saturating concentrations of 9AA.Addition of Mg2+ partially reversed the binding of 9AA in chloroplasts in the dark as observed by a Mg2+-induced increase of 9AA fluorescence as well as by spectrophotom etric measurements of free 9AA. It appeared, however, that use of fluorescence techniques for m easuring free 9AA introduced an error in the estimation of the m agnitude of binding, particularly at low concentration of 9AA ( < 7 5 μM). This is probably due to change in fluorescence yield of membrane-bound 9AA on addition of cations. The nature of the binding of 9AA to the thylakoid membranes and the effects of Mg2+ thereupon suggest that both chemical binding of cations and screening of surface charge of the mem branes should be considered in discussing the mechanism of cation action on chloroplast structure and function. Interpretation of these data with respect to heterogeneity of sites of cation action upon or within chloroplast membranes is discussed.

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