Flying splice

Figure 18.3 is an extrusion line schematic drawing of tension control equipment for the unwinding substrate. The arrows indicate the motions of the driven tension control rolls and idlers as well as the substrate, and the direction of outward pressure-on the rolls. Figure 18.4 is what is called a flying splice on a double-station-unrolling stand where ... 

Human genes do more work than those of the roundworm or fruit fly (eg, alternative splicing is used more frequently). 

Schimanski B, Brandenbu J. Nguyen TN et al. A TFIIB-like protein is indispensable for spliced leader RNA gene transcription in Trypanosoma brucei. NucI Acids Res 2006 34(6) 1676-1684. Anantharaman V, Aravind L, Koonin EV. Emergence of diverse biochemical activities in evolutionarily conserved structural scaffolds of proteins. Curr Opin Chem Biol 2003 7(l) 12-20. Clayton CE. Life without ttanscriptional control From fly to man and back ain. EMBO J 2002 21(8) 1881-1888. 

As described, Da5-Da7 subunits are most closely related to vertebrate a7, sharing 45% peptide sequence identity. Dal-Da4 and Dfil-Dfil are most closely related to each other (30-50% identity), reflecting 25-40% identity with vertebrate. Da3 is the most distantly related, showing only 20% sequence identity with other nAChR subunits of both invertebrates and vertebrates. Da2 shares the closest sequence identity with other insect a subunits. Additional diversity of Drosophila nAChRs arises from alternative splicing (4 of the 10 subunits), and RNA editing (first described for nAChRs in the fly) [56] serves to dramatically increase the number of possible subunit isoforms (over 30 000 Da6 isoforms are theoretically possible). 

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