Glycan-Based Cellular Communication: Techniques for Carbohydrate-Protein Interactions

2020 ◽  
Author(s):  
S.B. Andrews ◽  
R.D. Leapman ◽  
P.E. Gallant ◽  
T.S. Reese

As part of a study on protein interactions involved in microtubule (MT)-based transport, we used the VG HB501 field-emission STEM to obtain low-dose dark-field mass maps of isolated, taxol-stabilized MTs and correlated these micrographs with detailed stereo images from replicas of the same MTs. This approach promises to be useful for determining how protein motors interact with MTs. MTs prepared from bovine and squid brain tubulin were purified and free from microtubule-associated proteins (MAPs). These MTs (0.1-1 mg/ml tubulin) were adsorbed to 3-nm evaporated carbon films supported over Formvar nets on 600-m copper grids. Following adsorption, the grids were washed twice in buffer and then in either distilled water or in isotonic or hypotonic ammonium acetate, blotted, and plunge-frozen in ethane/propane cryogen (ca. -185 C). After cryotransfer into the STEM, specimens were freeze-dried and recooled to ca.-160 C for low-dose (<3000 e/nm2) dark-field mapping. The molecular weights per unit length of MT were determined relative to tobacco mosaic virus standards from elastic scattering intensities. Parallel grids were freeze-dried and rotary shadowed with Pt/C at 14°.


2013 ◽  
Vol 54 ◽  
pp. 79-90 ◽  
Author(s):  
Saba Valadkhan ◽  
Lalith S. Gunawardane

Eukaryotic cells contain small, highly abundant, nuclear-localized non-coding RNAs [snRNAs (small nuclear RNAs)] which play important roles in splicing of introns from primary genomic transcripts. Through a combination of RNA–RNA and RNA–protein interactions, two of the snRNPs, U1 and U2, recognize the splice sites and the branch site of introns. A complex remodelling of RNA–RNA and protein-based interactions follows, resulting in the assembly of catalytically competent spliceosomes, in which the snRNAs and their bound proteins play central roles. This process involves formation of extensive base-pairing interactions between U2 and U6, U6 and the 5′ splice site, and U5 and the exonic sequences immediately adjacent to the 5′ and 3′ splice sites. Thus RNA–RNA interactions involving U2, U5 and U6 help position the reacting groups of the first and second steps of splicing. In addition, U6 is also thought to participate in formation of the spliceosomal active site. Furthermore, emerging evidence suggests additional roles for snRNAs in regulation of various aspects of RNA biogenesis, from transcription to polyadenylation and RNA stability. These snRNP-mediated regulatory roles probably serve to ensure the co-ordination of the different processes involved in biogenesis of RNAs and point to the central importance of snRNAs in eukaryotic gene expression.


Author(s):  
Maya Henry

Abstract Primary progressive aphasia (PPA) is a relatively new diagnostic entity, for which few behavioral treatments have been investigated. Recent work has helped to clarify the nature of distinct PPA variants, including a nonfluent variant (NFV-PPA), a logopenic variant (LV-PPA), and a semantic variant (SV-PPA). This paper reviews treatment research to date in each subtype of PPA, including restitutive, augmentative, and functional approaches. The evidence suggests that restitutive behavioral treatment can result in improved or stabilized language performance within treated domains. Specifically, sentence production and lexical retrieval have been addressed in NFV-PPA, whereas lexical retrieval has been the primary object of treatment in LV and SV-PPA. Use of augmentative communication techniques, as well as implementation of functional communication approaches, also may result in improved communication skills in individuals with PPA. The ideal treatment approach may be one that combines restitutive, augmentative, and functional approaches to treatment, in order to maximize residual cognitive-linguistic skills in patients. Additional research is warranted to determine which modes of treatment are most beneficial in each type of PPA at various stages of severity.


2011 ◽  
Vol 49 (08) ◽  
Author(s):  
LC König ◽  
M Meinhard ◽  
C Sandig ◽  
MH Bender ◽  
A Lovas ◽  
...  

1974 ◽  
Vol 31 (03) ◽  
pp. 403-414 ◽  
Author(s):  
Terence Cartwright

SummaryA method is described for the extraction with buffers of near physiological pH of a plasminogen activator from porcine salivary glands. Substantial purification of the activator was achieved although this was to some extent complicated by concomitant extraction of nucleic acid from the glands. Preliminary characterization experiments using specific inhibitors suggested that the activator functioned by a similar mechanism to that proposed for urokinase, but with some important kinetic differences in two-stage assay systems. The lack of reactivity of the pig gland enzyme in these systems might be related to the tendency to protein-protein interactions observed with this material.


1965 ◽  
Vol 14 (03/04) ◽  
pp. 431-444 ◽  
Author(s):  
E. R Cole ◽  
J. L Koppel ◽  
J. H Olwin

SummarySince Ac-globulin (factor V) is involved in the formation of prothrombin activator, its ability to complex with phospholipids was studied. Purified bovine Ac-globulin was complexed to asolectin, there being presumably a fixed number of binding sites on the phospholipid micelle for Ac-globulin. In contrast to the requirement for calcium ions in the formation of complexes between asolectin and autoprothrombin C, calcium ions were not required for complex formation between asolectin and Ac-globulin to occur ; in fact, the presence of calcium prevented complex formation occurring, the degree of inhibition being dependent on the calcium concentration. By treating isolated, pre-formed aso- lectin-Ac-globulin complexes with calcium chloride solutions, Ac-globulin could be recovered in a much higher state of purity and essentially free of asolectin.Complete activators were formed by first preparing the asolectin-calcium- autoprothrombin C complex and then reacting the complex with Ac-globulin. A small amount of this product was very effective as an activator of purified prothrombin without further addition of calcium or any other cofactor. If the autoprothrombin C preparation used to prepare the complex was free of traces of prothrombin, the complete activator was stable for several hours at room temperature. Stable preparations of the complete activator were centrifuged, resulting in the sedimentation of most of the activity. Experimental evidence also indicated that activator activity was highest when autoprothrombin C and Ac-globulin were complexed to the same phospholipid micelle, rather than when the two clotting factors were complexed to separate micelles. These data suggested that the in vivo prothrombin activator may be a sedimentable complex composed of a thromboplastic enzyme, calcium, Ac-globulin and phospholipid.


2018 ◽  
Vol 9 (07) ◽  
pp. 20880-20885
Author(s):  
Luh Kadek Budi Martini ◽  
Putu Sri Astuti ◽  
Luh Komang Candra Dewi

Challenges by traditional fruit market traders in Denpasar are weaknes in business management, bookkeeping administration sales strategy, buyers service, communication techniques, and rotten fruits that do not sell yet untapped. The purposes of this empowerment are to (1 ) improvement of business management, (2) increased of knowledge for traders: bookkeeping administration is the procedure of recording financial transactions and can easily perform financial analysis, sales strategy, especially arrangement of merchandise (display), service to buyers, communication techniques and transactions honest but still profitable, (3) utilization of rotten fruit that is not sold to be processed into MOL (local microorganisms) for the manufacture of organic fertilizers in the household scale. The method used is counseling and training. The results of the activities are as follows: 1) fruit trader group can already well manage its trading business.2) fruit trader group can make good administration and business bookkeeping 3) fruit trader group can make marketing strategy by arranging (display) with well, and already use Show Case for display merchandise, customer visits increased 25%. 4) Fruit merchant group can already utilize rotten fruit as MOL for liquid crop fertilizer


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