RT-PCR analysis of alternative splicing of SYBL1. Sizes (in base pairs) of MW markers and expected lengths of amplified fragments are reported. Isoforms and corresponding amplified fragments are color coded. Exonic structure of VAMP7a has grey background. The photographs show RT-PCR amplifications using cDNAs from tissues (1-19) or cell lines (20-27): 1, fetal brain; 2, total brain; 3, hippocampus; 4, cerebellum; 5, fetal heart; 6, heart; 7, skeletal muscle; 8, fetal liver; 9, liver; 10, mammary gland; 11, testis; 12, ovary: 13, pancreas; 14, kidney; 15, spleen; 16, colon; 17, small intestine; 18, stomach; 19, placenta; 20, T lymphocytes; 21, Raji; 22, HeLa; 23, RPE; 24, U937; 25, HEK293; 26, ND2; 27, ND2 15 days after induction. Panel A: variants missing the LD (VAMP7c, red; VAMP7d, orange; VAMP7h, yellow) were identified using SYN1F/R primers, placed on exon 2-containing ATG and exon 4. Panel B: structures of the VAMP7d and VAMP7h mRNAs and analysis of translation initiation sites (TIS). The nucleotide context for each TIS is aligned to the mammalian consensus (R, purine = A/G); nucleotides crucial to optimal initiation are green. Arrows indicate optimal (green) and non-optimal (black) TIS; red circles are stop codons. SNARE motif (cyan), conserved arginine (black vertical bar) and transmembrane region with intravesicular tail (light green) are also reported. Panel C: non-SNARE variants (VAMP7b, dark blue; VAMP7i, blue; VAMP7j, light blue) were identified by semi-nested RT-PCR with a VAMP7a specific ASOa primer (SYB2/3F) combined to a 3'UTR primer (Tel3) then to a nested primer (TBP5).