A researcher is interested in the proteins that E-cadherin binds to. She expresses full-length E-cadherin as well some t

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A Researcher Is Interested In The Proteins That E Cadherin Binds To She Expresses Full Length E Cadherin As Well Some T 1 (178.68 KiB) Viewed 24 times

A researcher is interested in the proteins that E-cadherin binds to. She expresses full-length E-cadherin as well some truncated constructs of the protein in a mouse cell line that does not express any other cadherins. The scheme of constructs is shown in figure A, (E represents the extracellular domain, TM the transmembrane domain and C the cytoplasmic domain). She labels the cells with 35S methionine for 16 hours, homogenizes them in detergent, and an antibody raised against the extracellular domain of the cadherin E-cadherin to pull-down (co-immunoprecipitate) E-cadherin and any associated proteins. She then analyses the immune precipitates by electrophoresis by SDS-PAGE, followed by autoradiography to make the labelled proteins visible. In lane 1 of figure B, the antibody precipitates three major proteins in cells transfected with a plasmid expressing the full-length intact cadherin. These proteins are not precipitated from untreated control cells. H₂N A 553aa B kd 200 - 97- 67- 45- 24 aa www. um m M Full-length E 31 aa 70 aa 105 aa E-Cad 437 E-Cad 48 TM C COOH 151 aa E-Cad 431 E-Cad 470 E-Cad 105 control 1 2 3 4 5 6 7 37 aa b. Which segment of cadherin is responsible for binding to other proteins? (2 marks) Full-length E-Cad 437 E-Cad 48 E-Cad 431 E-Cad 470 E-Cad A105 a. Which protein bands in the autoradiograph (Figure B) correspond to cadherin and which correspond to proteins that bind to cadherin? Explain your answer. (2 marks)