Abstract: Disclosed herein are methods for performing assays, including general functional assays, on a biological cell. Also disclosed herein are methods of barcoding the 5? ends of RNA from a biological cell and methods of preparation of expression constructs from the barcoded RNA. The barcoded RNA can encode proteins of interest, such as B cell receptor (BCR) heavy and light chain sequences. The expression constructs can be generated individually or in a paired/multiplexed manner, allowing rapid re-expression of individual proteins or protein complexes.

Abstract: Methods are described herein for screening an antibody producing cell within a microfluidic environment. The antibody producing cell may be a B cell lymphocyte, which may be a memory B cell or a plasma cell. An antigen of interest may be brought into proximity with the antibody producing cell and binding of the antigen by an antibody produced by the antibody producing cell may be monitored. Methods of obtaining a sequencing library from an antibody producing cell are also described.