scholarly journals Breaching the diffusion barrier that compartmentalizes the transmembrane glycoprotein CE9 to the posterior-tail plasma membrane domain of the rat spermatozoon.

1993 ◽  
Vol 120 (3) ◽  
pp. 687-694 ◽  
Author(s):  
C L Nehme ◽  
M M Cesario ◽  
D G Myles ◽  
D E Koppel ◽  
J R Bartles

CE9 is a posterior-tail domain-specific integral plasma membrane glycoprotein of the rat testicular spermatozoon. During epididymal maturation, CE9 undergoes endoproteolytic processing and then redistributes into the anterior-tail plasma membrane domain of the spermatozoon (Petruszak, J. A. M., C. L. Nehme, and J. R. Bartles. 1991. J. Cell. Biol. 114:917-927). We have determined the sequence of CE9 and found it to be a Type Ia transmembrane protein identical to the MRC OX-47 T-cell activation antigen, a member of the immunoglobulin superfamily predicted to have two immunoglobulin-related loops and three asparagine-linked glycans disposed extracellularly. Although encoded by a single gene and mRNA in the rat, the majority of spermatozoal CE9 is of smaller apparent molecular mass than its hepatocytic counterpart due to the under-utilization of sites for asparagine-linked glycosylation. By fluorescence recovery after photobleaching, CE9 was determined to be mobile within the posterior-tail plasma membrane domain of the living rat testicular spermatozoon, thus implying the existence of a regional barrier to lateral diffusion that is presumed to operate at the level of the annulus. Through the development of an in vitro system, the modification of this diffusion barrier to allow for the subsequent redistribution of CE9 into the anterior-tail domain was found to be a time-, temperature-, and energy-dependent process.

1994 ◽  
Vol 107 (2) ◽  
pp. 561-570 ◽  
Author(s):  
M.M. Cesario ◽  
J.R. Bartles

Western blotting, immunofluorescence and immunogold electron microscopy were used to examine the compartmentalization, processing and redistribution of the integral plasma membrane protein CE9 on the spermatozoa of rats, mice and hamsters. In each species examined, spermatozoal CE9 was found to undergo endoproteolytic processing followed by a net redistribution from the posterior-tail domain into the anterior-tail domain of the plasma membrane during epididymal maturation. Compared to spermatozoa of the rat and mouse, those of the hamster were found to express a greater proportion of their CE9 within the anterior-tail plasma membrane domain at all stages of maturation. As a consequence, CE9 was judged to be a suitable marker for two different spermatozoal plasma membrane domains: the posterior-tail plasma membrane domain (spermatozoa from the testis and caput epididymidis of the rat and mouse) and the anterior-tail domain (spermatozoa from the cauda epididymidis of the hamster). Immunogold electron microscopy was used to pinpoint the positions of the boundaries of these CE9-containing plasma membrane domains at a high level of resolution. In each case, the position of the CE9 domain boundary was found to be strongly correlated with that of the subplasmalemmal electron-dense ring known as the annulus. The precise spatial relationship between the CE9 domain boundary and the annulus was, however, found to differ significantly among species and/or as a function of maturation.


Author(s):  
Annette Brandel ◽  
Sahaja Aigal ◽  
Simon Lagies ◽  
Manuel Schlimpert ◽  
Ana Valeria Meléndez ◽  
...  

AbstractThe opportunistic pathogen Pseudomonas aeruginosa has gained precedence over the years due to its ability to develop resistance to existing antibiotics, thereby necessitating alternative strategies to understand and combat the bacterium. Our previous work identified the interaction between the bacterial lectin LecA and its host cell glycosphingolipid receptor globotriaosylceramide (Gb3) as a crucial step for the engulfment of P. aeruginosa via the lipid zipper mechanism. In this study, we define the LecA-associated host cell membrane domain by pull-down and mass spectrometry analysis. We unraveled a predilection of LecA for binding to saturated, long fatty acyl chain-containing Gb3 species in the extracellular membrane leaflet and an induction of dynamic phosphatidylinositol (3,4,5)-trisphosphate (PIP3) clusters at the intracellular leaflet co-localizing with sites of LecA binding. We found flotillins and the GPI-anchored protein CD59 not only to be an integral part of the LecA-interacting membrane domain, but also majorly influencing bacterial invasion as depletion of either of these host cell proteins resulted in about 50% reduced invasiveness of the P. aeruginosa strain PAO1. In summary, we report that the LecA-Gb3 interaction at the extracellular leaflet induces the formation of a plasma membrane domain enriched in saturated Gb3 species, CD59, PIP3 and flotillin thereby facilitating efficient uptake of PAO1.


1989 ◽  
Vol 109 (6) ◽  
pp. 2783-2790 ◽  
Author(s):  
A J Jesaitis ◽  
J O Tolley ◽  
G M Bokoch ◽  
R A Allen

Isolated purified plasma membrane domains from unstimulated human neutrophils were photoaffinity labeled with F-Met-Leu-Phe-N epsilon-(2-(p-azido-[125I]salicylamido)ethyl- 1,3'-dithiopropionyl)-Lys also referred to as FMLPL-SASD[125I]. Most of the photoaffinity-labeled N-formyl peptide receptors were found in light plasma membrane fraction (PM-L) which has been previously shown to be enriched in guanyl nucleotide binding proteins and the plasma membrane marker alkaline phosphatase (Jesaitis, A. J., G. M. Bokoch, J. O. Tolley, and R. A. Allen. 1988. J. Cell Biol. 107:921-928). Furthermore, the heavy plasma membrane fraction (PM-H), which is enriched in actin and fodrin, was depleted in receptors. Solubilization of PM-L and PM-H in divalent cation-free buffer containing octylglucoside and subsequent sedimentation at 180,000 g in detergent-containing sucrose gradients revealed two receptor forms. The major population, found in PM-L sedimented as a globular protein with an apparent sedimentation coefficient of 6-7S, while a minor fraction found in the PM-H fraction sedimented as a 4S particle. In addition, the 6-7S form could be converted to the 4S form by inclusion of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) in the extraction buffer (ED50 = 10-30 nM). ATP was not effective at doses of up to 10 microM. In contrast, isolation and solubilization of receptors from desensitized cells (photoaffinity labeled after a 15 degrees C incubation with FMLPL-SASD[125I]) revealed that the majority of receptors (greater than 60-90%), which are found in PM-H, sedimented as 4S particles. A minor fraction of receptors found in the PM-L sedimented as 6-7S species. The receptors in the PM-H fraction, however, were still capable of interacting with G-proteins, since addition of unlabeled PM-L membrane fraction as a G-protein source reconstituted a more rapidly sedimenting form showing sensitivity to GTP gamma S. These results suggest that receptors in unstimulated human neutrophils have a higher probability of interacting with G-proteins because they are in the light plasma membrane domain. The results also suggest that receptors that have been translocated to the heavy plasma membrane domain during the process of desensitization or response termination have a lower probability of interacting with G-protein. Since the latter receptors are still capable of forming G protein associations, then their lateral segregation would represent a mechanism of controlling of receptor G-protein interactions. This reorganization of the plasma membrane, therefore, may form the molecular basis for response termination or homologous desensitization in human neutrophils.


1998 ◽  
Vol 46 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Lukas Landmann ◽  
Sabine Angermüller ◽  
Christoph Rahner ◽  
Bruno Stieger

Hepatocellular Na+,K+-ATPase is an important driving force for bile secretion and has been localized to the basolateral plasma membrane domain. Cholestasis or impaired bile flow is known to modulate the expression, domain specificity, and activity of various transport systems involved in bile secretion. This study examined Na+,K+-ATPase after ethinylestradiol (EE) treatment and after bile duct ligation (BDL), two rat models of cholestasis. It applied quantitative immunoblotting, biochemical and cytochemical determination of enzyme activity, and immunocytochemistry to the same livers. The data showed a good correlation among the results of the different methods. Neither EE nor BDL induced alterations in the subcellular distribution of Na+,K+-ATPase, which was found in the basolateral but not in the canalicular (apical) plasma membrane domain. Protein expression and enzyme activity showed a small (~10%) decrease after EE treatment and a similar increase after BDL. These modest changes could not be detected by immunofluorescence, immuno EM, or cytochemistry. The data, therefore, demonstrate that Na+,K+-ATPase is only slightly affected by EE and BDL. They suggest that other components of the bile secretory apparatus that take effect downstream of the primary basolateral driving force may play a more prominent role in the pathogenesis of cholestasis.


1994 ◽  
Vol 301 (3) ◽  
pp. 671-674 ◽  
Author(s):  
D A Novak ◽  
M S Kilberg ◽  
M J Beveridge

Na(+)-independent hepatic transport of branched-chain amino acids occurs via at least two distinct transport processes. System L1, characterized by micromolar Km values, predominates in hepatoma and fetal hepatocytes, whereas System L2, distinguished by Km values in the millimolar range and sensitivity to inhibition by N-ethylmaleimide (NEM), predominates in adult hepatocytes. To determine the plasma-membrane domain localization and ontogeny of System L activity in the rat, we prepared membrane vesicles from the livers of suckling (10 days old) and adult rats enriched for either basolateral (BLMV) or canalicular (CMV) domains. The initial rate of [3H]leucine uptake into BLMV and CMV derived from adult liver was significantly inhibited by the addition of 5 mM NEM; transport into BLMV and CMV derived from 10-day-old rat liver was not affected. Michaelis-Menten kinetic parameters estimated in BLMV derived from adult liver were consistent with System L2 (Km = 2.16 +/- 0.62 mM, Vmax. = 781 +/- 109 pmol/5 s per mg of protein), as were those estimated in adult CMV (Km = 0.83 +/- 0.21 mM, Vmax. = 385 +/- 38 pmol/5 s per mg of protein). Conversely, kinetic parameters estimated in BLMV derived from livers of suckling rats were consistent with System L1 (Km = 0.041 +/- 0.024 mM, Vmax. = 8.8 +/- 1.5 pmol/5 s per mg of protein), as were those from CMV of suckling rats (Km = 0.023 +/- 0.09 mM, Vmax. = 28.1 +/- 2.1 pmol/5 s per mg of protein). We conclude that NEM-inhibitable Na(+)-independent leucine transport activity consistent with System L2 is present in both BLMV and CMV derived from adult rat liver, whereas System L1 predominates in 10-day-old rat liver tissue.


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