Alternative splicing takes place in basically all eukaryotic cells with the typical eukaryotic exon-intron gene architecture. And most of it really is noise.
No, it’s a conclusion to a long argument from making sense of enormous amounts of data.
It also straightforwardly contradicts how creationists such as yourself usually think about protein sequence space. Thinking that all or most alternative splice protein isoforms are functional proteins implies that there is much more relaxed constraints on protein sequence function than anything you’d normally be arguing. You’re literally positing that you can take essential proteins, be it metabolic enzymes, transcriptional regulators, structural proteins or what have you, remove something like half or a third of one or multiple domains, copy-paste different parts together in new ways, and still get useful proteins with new functions that are active in anything from metabolism to multicellular and embryonic development.
If you’re so willing to believe that just because you’re simultaneously unwilling to believe there is that junk DNA, junk-activity, and much noise in biology, then I think perhaps your mind deserves a vacation from the sheer compartmentalization and cognitive dissonance you must be engaging in. I’ll be welcoming your support and agreement to what I’ve been arguing over in the Functions are not so rare at all, and definitely not isolated, in sequence space of biopolymers thread.
Bill Cole - super-evolutionist.
Active =/= has fitness-relevant functions. As the ENCODE fiasco should have taught you.
Alternative splicing is active in all tissues, at varying levels, for different genes. Mostly at low levels, and mostly it’s unavoidable byproducts of the inherent uncertainties in the splicing mechanism.
Different organisms show different levels of splicing activity, and it varies among tissues, but with more closely related species generally having more similar splicing patterns (just as any other molecular and genetics-related divergence), which is still entirely consistent with the vast majority of splicing constituting unavoidable biochemical noise.