Posttranslational modification of human T-cell growth factor.

Area of Science:

• Biochemistry
• Molecular Biology
• Immunology

Background:

• Human T-cell growth factor (TCGF) is crucial for T-cell proliferation.
• Post-translational modifications can significantly impact protein function and antibody binding.

Purpose of the Study:

• To identify the specific modification at the amino-terminus of human TCGF.
• To characterize the N-terminal amino acid and its attached moiety.
• To assess the functional relevance of this modification for antibody recognition.

Main Methods:

• Amino-terminal sequence analysis of human TCGF.
• Analysis of the N-terminal octapeptide using amino acid analysis.
• Mass spectrometry to determine the molecular mass and structure of the modification.

Main Results:

• The amino acid at position 3 of the polypeptide chain was identified as modified.
• This modification was determined to be N-acetyl-D-galactosamine linked to threonine.
• The glycosylation site at position 3 influences the binding selectivity of a specific monoclonal antibody.

Conclusions:

• The N-terminus of human TCGF features a threonine residue at position 3 that is glycosylated with N-acetyl-D-galactosamine.
• This specific glycosylation site is important for the recognition by certain monoclonal antibodies, impacting their selectivity.