Cloning and characterization of a cDNA encoding human differentiation antigen 5D4

Area of Science:

• Molecular Biology
• Immunology
• Cell Biology

Background:

• Monoclonal antibody (mAb) 5D4 exhibits differential reactivity with human B and T cell lines.
• Investigating the molecular targets of mAb 5D4 is crucial for understanding immune cell interactions.

Purpose of the Study:

• To isolate and characterize the complementary DNA (cDNA) recognized by mAb 5D4.
• To determine the protein structure and potential cellular localization of the identified molecule.

Main Methods:

• cDNA library screening using mAb 5D4 as a probe.
• Reverse transcription polymerase chain reaction (RT-PCR) for mRNA detection.
• Northern blot analysis and sequence analysis for cDNA characterization.
• Secondary structure prediction for protein analysis.

Main Results:

• A 1,846 bp full-length cDNA was isolated from a human tonsil cell library.
• The cDNA encodes a 374 amino acid (AA) protein with an open reading frame.
• The protein contains a hydrophobic region and a predicted transmembrane helix (AA 313-334) oriented inside-out.
• Differential mRNA expression observed in B cell lines (3D5, Daudi) and T cell lines (Jurkat).

Conclusions:

• The isolated cDNA represents a full-length transcript encoding a transmembrane protein.
• The protein's characteristics suggest a role in cell membrane function, potentially in B cells.
• Further studies are warranted to elucidate the specific function of this protein in immune cells.