Encoding A New Differentiation Antigen 5c5 And 5d4 Full-length Cdna Of Cloning, Sequence Analysis And Expression

Differentiation antigen is also called cluster of differentiation (CD) which possesses very important biological significance. Up to date, 166 CDs have been nominated by the Conference and Workshop on Human Leucocyte Differentiation Antigens. In recent years, the studies on the structure and the function of some CDs have progressed a lot with the application of the knodwledge and technique of molecular biology to Immunology.The aim of this thesis is to find and clone cDNAs encoding new differentiation antigens, and to determine their nucleotide sequences, and to analyze their expression from the point of either protein or mRNA.The thesis mainly contains two parts:1.5C5 cDNAA 613bp cDNA has been isolated from a human tonsil cell λgt11 cDNA library (ATCC No.37545) by using a mixture of McAb 5C5 and McAb 5C5-G₁ developed in our lab several years ago as a probe. Since the cDNA was not a full length one, the first step of my project was to isolate its full-length cDNA. With its 5' end 467bp fragment as a probe, only one positive clone which length and sequence was completely the same as those of the 467bp cDNA probe was obtained in the screening from other one human tonsil cell λgt11cDNA library(ATCC No.37546). Since McAbs 5C5 and McAb 5C5-G₁ were developed by means of immunization of mouse with 3D5 cells and screening with 3D5 cell as target, a 3D5 cell λgt11 cDNA library was constructed. The λ phage titer of the libray is 1.1×10⁶ and the recombination rate is 97.5%. The lengths of the inserted fregments are around 0.4 to 2.5kb with an average of 1.6kb. Seventeen positive clones have been isolated from this library in a screening. Part out of the isolated cDNA were 0.9Kb long, and the others 0.7kb long. So, two cDNA sequences with the lengths of 908bp and 746bp named 5C5-1 cDNA and 5C5-2 cDNA have be obtained. There exists an open reading frame in 5C5-1 cDNA from 19bp to 846bp, which encodes a 276 amino acid protein. The protein has two hydrophobic areas from 85 to 110AA and 180 to 200AA.