Teratocarcinoma cell adhesion: identification of a cell-surface protein involved in calcium-dependent cell...

Area of Science:

• Cell Biology
• Developmental Biology
• Biochemistry

Background:

• Teratocarcinoma cells exhibit calcium-dependent cell-cell adhesion mediated by a unique site (t-CDS).
• This t-CDS is uniquely inactivated by trypsin in the absence of calcium ions (Ca2+).

Purpose of the Study:

• To identify the molecular components responsible for the calcium-dependent cell-cell adhesion in teratocarcinoma cells.
• To characterize the role of specific cell surface antigens in mediating teratocarcinoma cell aggregation and monolayer formation.

Main Methods:

• Utilized Fab fragments of antibodies against trypsin- and calcium-treated F9 teratocarcinoma cells (anti-TC-F9) to inhibit cell aggregation.
• Performed absorption experiments with treated F9 cells (TC-F9 and TE-F9) to identify specific antigens.
• Employed immunoprecipitation and molecular weight analysis to characterize cell surface components.
• Investigated the effect of a released substance (p34) on antibody binding and cell dissociation.

Main Results:

• Anti-TC-F9 Fab fragments inhibit teratocarcinoma cell aggregation mediated by t-CDS.
• A specific component, p140 (molecular weight ~140,000), was identified on TC-F9 cells and is recognized by anti-TC-F9.
• A tryptic fragment, p34 (molecular weight ~34,000), released from TC-F9 cells, neutralized the inhibitory effect of anti-TC-F9 Fab and interfered with p140 immunoprecipitation.
• Anti-TC-F9 Fab induced dissociation of teratocarcinoma cell monolayers, an effect neutralized by p34.

Conclusions:

• The component p140 is essential for the function of the calcium-dependent cell-adhesion site (t-CDS) in teratocarcinoma cells.
• p140 is identified as a cell-adhesion molecule critical for establishing teratocarcinoma cell monolayers.
• p34 represents a tryptic fragment of p140, further supporting p140's role in cell adhesion.