
Product Description
Natural human C4a is prepared by cleavage of human C4 protein by human C1s. It is produced during activation of both the classical and lectin pathways of complement.C4a is a member of the anaphylatoxin family of three proteins (C3a, C4a and C5a) produced by the activation of complement (Hugli, T.E. et al. (1981)).It is an unglycosylated polypeptide containing 77 amino acids with a molecular mass of 8,759 daltons.Many of the biological functions of C4a are similar to those of C3a, but the specific activities are far below those of C3a.C4a activity is so low, in fact, that it was initially thought to be inactive.These measured activities include inducing muscle contraction in the guinea pig ileum test (spasmogenic activity), desensitization of muscle to C3a stimulation suggesting that the same receptor for both C3a and C4a is involved (tachyphylactic activity) and inducing vascular permeability in human skin (Gorski J.P. et al. (1979)).C4a does not show tachyphylactic activity against C5a or chemotactic activity.Removal of the C-terminal arginine by serum carboxypeptidase N destroys all these activities (Meuller-Ortiz, S.L., et al. (2009)).C4a appears to act through the C3a receptor (C3aR) which is a G-protein coupled receptor found widely distributed on peripheral tissues, lymphoid cells (neutrohphils, monocyes, and eosinophils) and in the central nervous system (astrocytes, neurons and glial cells) (Law, S.K.A. and Reid, K.B.M. (1995)).
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NaturalProteinStopsDeadlyHumanBrainCancerInMice
ScientistsfromJohnsHopkinsandfromtheUniversityofMilanhaveeffectivelyproventhattheycaninhibitlethalhumanbraincancersinmiceusingaproteinthatselectivelyinducespositivechangesintheactivityofcellsthatbehavelikecancerstemcells.ThereportispublishedinNature.
Themostcommontypeofbraincancer-glioblastoma-ismarkedbythepresenceofthesestem-cell-likebraincells,which,insteadoftriggeringthereplacementofdamagedcells,formcancertissue.Stemcells,unlikeallothercellsinthebody,arecapableofformingalmostanykindofcellwhentheright"signals"triggertheirdevelopment.
Fortheirtreatmentexperiment,theresearchersreliedonaclassofproteins,bonemorphogenicproteins,thatcauseneuralstem-cell-likeclusterstolosetheirstemcellproperties,whichinturnstopstheirABIlitytodivide.
Firsttheypretreatedhumanglioblastomacellswithbonemorphogenicprotein4(BMP4),theninjectedthesetreatedcellsintomousebrains.Inmiceinjectedwithcellsthatwerenotpretreated,large,invasivecancersgrew.InthemicewithBMP4-treatedcells,nocancersgrewatall.Threetofourmonthsafterinjection,allmicethatgotuntreatedcellsdied,andnearlyallmicewithBMP4-treatedcellswerealive.
Next,thescientistsdeliveredslow-releaseBMP4-containing"beads"directlyintomousebrainswithimplantedglioblastomacells.Micethatgotemptybeadsdevelopedlargemalignanttumorsanddied.MicewithBMP4beadssurvivedmuchlonger,and80percentsurvivedfourmonthsaftercancercellimplants.
"OurideaistotreatpatientswithBMP4orsomethinglikeitrightaftersurgerytoremoveglioblastomainhopesofpreventingtheregrowthofthecancerandimprovingsurvivaltime,"saysAlessandroOlivi,M.D.,directoroftheDivisionofNeurosurgicalOncologyatHopkinsandacontributortothestudy.
OlivisaysclinicalstudiesusingBMP4couldbeginwithinayearand,ifsuccessful,drugtherapiescouldbeavailabletothepublicwithinthreetofouryears.
"ThiswasproofoftheideathatBMPscouldstopglioblastomabydepletingthestem-cell-likepopulationthatfeedsit,"saysHenryBrem,M.D.,chairmanoftheDepartmentofNeurosurgeryatHopkinsandacollaboratorinthestudy."Thisopensexcitingdoorstofutureresearchintotreatmentsandtherapiesforsuchadevastatingdisease."
算上其他生物24种
大概是记不太清了
本人目前需从电鳗放电器官中提取乙酰胆碱受体蛋白,提纯需要的步骤和电鳗器官都可以提供,有没有提供外包提纯服务的公司或者实验室。

