Figure 2.

Characterization of neuroligin splice variants in pancreatic β-cells. A, Schematic representation of alternative splice inserts in neuroligin (NL) gene family members. Splice site A is present in all neuroligin family members, whereas splice site B is only present in neuroligin-1. Different alternative exons (A1–A3) can be included at site A. B–D, To determine which neuroligin splice variants are expressed in islets (Isl), primers were designed to either flank or sit on each of the known neuroligin splice inserts. PCR was performed using cDNA from either human islets or INS-1 (Ins) cells and from either human or rat brain (Br). Each of the known splice inserts in neuroligin-1 (B), neuroligin-2 (C), and neuroligin-3 (D) was detected in both human islets and INS-1 cells. Transcripts lacking inserts at splice site A in neuroligin-1 were detected in human islets, rat brain, and INS-1 cells, but not in human brain (B, row 2). Neuroligin-1 transcripts lacking inserts at splice site B and neuroligin-2 inserts lacking site A were not detected in the brain, INS-1 cells, or human islets (bottom two panels of B and C). Neuroligin-3 transcripts lacking an insert at splice site A were detected in all tissues tested (D, bottom two panels). −, Absence of insert; Nt, no template; ++, presence of both inserts; +, presence of insert.