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Investigating the effect of salt concentrations on the immune cell membrane protein CD45 D1-D4 in a supported lipid bilayer using hydrodynamic trapping

Onema, Carl Eric LU (2017) KEMK07 20171
Department of Chemistry
Abstract
The immune system is a very complex system, aimed to protect the body from the many dangers that loom around us. A well-functioning immune system can fight of most invaders, remove foreign particles that entered our bodies, and take care of dead cells.

The aim in this work is seeing how the protein CD45 (also known as PTPRC, protein tyrosine phosphatase, receptor type, C) is affected by salt concentration, more exactly how it is oriented on a lipid bilayer. CD45 have been observed to be essential for proper activation of T cells, but exactly how this is achieved on a molecular level is not known. Since the protein interact with its environment, its orientation may play an important role for the sensitivity and function of CD45.

In... (More)
The immune system is a very complex system, aimed to protect the body from the many dangers that loom around us. A well-functioning immune system can fight of most invaders, remove foreign particles that entered our bodies, and take care of dead cells.

The aim in this work is seeing how the protein CD45 (also known as PTPRC, protein tyrosine phosphatase, receptor type, C) is affected by salt concentration, more exactly how it is oriented on a lipid bilayer. CD45 have been observed to be essential for proper activation of T cells, but exactly how this is achieved on a molecular level is not known. Since the protein interact with its environment, its orientation may play an important role for the sensitivity and function of CD45.

In order to investigate this, a combination of total internal reflection fluorescence microscopy, FRAP (fluorescence recovery after photobleaching) and hydrodynamic trapping have been used. The protein was attached to a supported lipid bilayer (SLB), which is a common cell membrane mimic. The orientation of the protein, i.e. its effective height, on the bilayer was measured using hydrodynamic trapping at different concentrations of sodium chloride at a physiological pH of 7.4. The diffusion of the protein across the SLB was also studied at different salt concentrations. The investigation implied a difference in the height of the proteins with it standing higher above the bilayer with increased salt concentration. This finding is important since it has consequences for how CD45 should be modelled on cell membrane mimics such as SLBs as well as on live cells. (Less)
Popular Abstract (Swedish)
Många av dem mest spektakulära händelserna som sker i vår värld kan inte ses med blotta ögat. Vid varje andetag sker miljontals reaktioner, saltkoncentrationen i cellerna regleras, signaler skickas genom kroppens nervsystem, och receptorer plockar upp signalmolekyler likt hur post skickas till brevlådan och läses av oss i hemmet.

Immunförsvaret är en otroligt viktig del av vår kropp som dagligen handskas med olika inkräktare som tar sig in i kroppen. Det ser till att sålla bort det som inte ska vara i kroppen likt hur reklamen sållas bort när det står ”ingen reklam” fastklistrat på brevlådan, eller så som spamfiltret i din e-post gör att mail med skadliga länkar hamnar i skräpposten.

Tänk dig nu att du ska hantera posten som kommer... (More)
Många av dem mest spektakulära händelserna som sker i vår värld kan inte ses med blotta ögat. Vid varje andetag sker miljontals reaktioner, saltkoncentrationen i cellerna regleras, signaler skickas genom kroppens nervsystem, och receptorer plockar upp signalmolekyler likt hur post skickas till brevlådan och läses av oss i hemmet.

Immunförsvaret är en otroligt viktig del av vår kropp som dagligen handskas med olika inkräktare som tar sig in i kroppen. Det ser till att sålla bort det som inte ska vara i kroppen likt hur reklamen sållas bort när det står ”ingen reklam” fastklistrat på brevlådan, eller så som spamfiltret i din e-post gör att mail med skadliga länkar hamnar i skräpposten.

Tänk dig nu att du ska hantera posten som kommer till hela ditt kvarter, eller låt säga att du ska hantera brevflödet som skickas till 100 personer, och det gäller att du sållar bort den oönskade reklamen. Du kan göra det själv, eller ta hjälp utav andra men när du gör detta måste du förse dem du tar hjälp av med energi och se till att de går hem igen när de inte finns något att göra så de inte blir rastlösa och börjar löpa amok! Lite så fungerar det med immunförsvaret. Det måste kunna svara i rätt proportioner, annars väntar problem.

I detta arbetet undersöktes en aspekt i immunförsvarets led som hanterar regleringen och initialiseringen av T-celler, B-celler samt andra typer av blodceller och går under namnet CD45. Protein har olika områden, aktiva säten, där reaktioner sker. Intresset för arbetet låg i att se hur en del av proteinet, CD45 D1-D4, orienterade sig i olika saltkoncentrationer med hjälp av en metod kallad ”Hydrodynamic Trapping”, en generell proteinfälla som utan direkt kontakt med proteinet samlar upp dem vid en punkt på en konstgjord cellyta kallad ”supported lipid bilayer”.

CD45 är ett protein som enbart finns på blodceller och på immunceller återfinns proteinet i ofantliga mängder. CD45 har i uppgift att slå på och av immuncellernas aktivitet då vissa immunceller kan vara för starka även för vår egen kropp. Att veta hur detta protein fungerar är av stor betydelse då immunförsvaret har stor betydelse för att vi ska kunna leva ett friskt liv. (Less)
Please use this url to cite or link to this publication:
author
Onema, Carl Eric LU
supervisor
organization
course
KEMK07 20171
year
type
M2 - Bachelor Degree
subject
keywords
Physical chemistry, Fysikalisk kemi
language
English
id
8913938
date added to LUP
2017-06-26 10:37:55
date last changed
2017-06-26 10:37:55
@misc{8913938,
  abstract     = {The immune system is a very complex system, aimed to protect the body from the many dangers that loom around us. A well-functioning immune system can fight of most invaders, remove foreign particles that entered our bodies, and take care of dead cells.

The aim in this work is seeing how the protein CD45 (also known as PTPRC, protein tyrosine phosphatase, receptor type, C) is affected by salt concentration, more exactly how it is oriented on a lipid bilayer. CD45 have been observed to be essential for proper activation of T cells, but exactly how this is achieved on a molecular level is not known. Since the protein interact with its environment, its orientation may play an important role for the sensitivity and function of CD45.

In order to investigate this, a combination of total internal reflection fluorescence microscopy, FRAP (fluorescence recovery after photobleaching) and hydrodynamic trapping have been used. The protein was attached to a supported lipid bilayer (SLB), which is a common cell membrane mimic. The orientation of the protein, i.e. its effective height, on the bilayer was measured using hydrodynamic trapping at different concentrations of sodium chloride at a physiological pH of 7.4. The diffusion of the protein across the SLB was also studied at different salt concentrations. The investigation implied a difference in the height of the proteins with it standing higher above the bilayer with increased salt concentration. This finding is important since it has consequences for how CD45 should be modelled on cell membrane mimics such as SLBs as well as on live cells.},
  author       = {Onema, Carl Eric},
  keyword      = {Physical chemistry,Fysikalisk kemi},
  language     = {eng},
  note         = {Student Paper},
  title        = {Investigating the effect of salt concentrations on the immune cell membrane protein CD45 D1-D4 in a supported lipid bilayer using hydrodynamic trapping},
  year         = {2017},
}