Note that this locus is complex: it appears to produce several proteins with no sequence overlap.
Expression: According to AceView, this gene is expressed at very high level, 4.8 times the average gene in this release. The sequence of this gene is defined by 563 GenBank accessions from 490 cDNA clones, some from brain (seen 43 times), lung (31), testis (20), eye (19), uterus (19), cerebellum (14), hippocampus (14) and 145 other tissues. We annotate structural defects or features in 30 cDNA clones.
Alternative mRNA variants and regulation: The gene contains 51 distinct introns (46 gt-ag, 4 gc-ag, 1 other). Transcription produces 32 different mRNAs, 27 alternatively spliced variants and 5 unspliced forms. There are 12 probable alternative promotors, 7 non overlapping alternative last exons and 5 validated alternative polyadenylation sites (see the diagram). The mRNAs appear to differ by truncation of the 5' end, truncation of the 3' end, presence or absence of 21 cassette exons, overlapping exons with different boundaries, splicing versus retention of 5 introns. 1911 bp of this gene are antisense to spliced gene SH2B3.aAug10, 180 to shorfu, raising the possibility of regulated alternate expression.
2 variants were isolated in vivo, despite the fact that they are predicted targets of nonsense mediated mRNA decay (NMD).
Efficacy of translation may be reduced by the presence of a shorter translated product (uORF) initiating at an AUG upstream of the main open reading frame (in variant aAug10, iAug10, kAug10, nAug10, pAug10).
Function: There are 64 articles specifically referring to this gene in PubMed. Functionally, the gene has been tested for association to diseases (OMIM: Spinocerebellar Ataxia 2; Other sources: Alzheimer Disease; Ataxia; Neuroblastoma; Parkinsonian Disorders; Spinocerebellar Degenerations) and proposed to participate in processes (cytoplasmic mRNA processing body assembly, regulation of translation, RNA metabolic process, RNA transport, stress granule assembly, cell death, negative regulation of multicellular organism growth). Proteins are expected to have molecular functions (protein binding, protein C-terminus binding, RNA binding) and to localize in various compartments (cytoplasm, Golgi apparatus, perinuclear region of cytoplasm, polysome, ribonucleoprotein complex, stress granule, trans-Golgi network and 4 others). Putative protein interactors have been described (A2BP1, ACTN1, ACTN2, ATXN1, BAT3, BIN1, CD247, CHGB, GFI1B, IDH3B, KIAA1279, LCP1, MSMBANDNCOA4, PABPC1, PLS3, SH3GL2, SH3GL3, TDRD7, VHL, ZNRD1).
Protein coding potential: 25 spliced and the unspliced mRNAs putatively encode good proteins, altogether 27 different isoforms (12 complete, 8 COOH complete, 7 partial), some containing domains LsmAD domain, Ataxin-2 C-terminal region [Pfam], some transmembrane domains, a N-myristoylation domain, a coiled coil stretch [Psort2]. The remaining 6 mRNA variants (2 spliced, 4 unspliced; 1 partial) appear not to encode good proteins.
3 isoforms are annotated using as Met a Kozak-compatible non-AUG start, thereby gaining a minimum of 66 amino acids N-terminal to the first AUG. Finally proteins from this gene may be modulated by acetylation; di-methylation; mono-methylation; phosphorylation; ubiquitination, as detailed at PhosphoSite.

Please quote: AceView: a comprehensive cDNA-supported gene and transcripts annotation, Genome Biology 2006, 7(Suppl 1):S12

Alternative mRNAs are shown aligned from 5' to 3' on a virtual genome where introns have been shrunk to a minimal length. Exon size is proportional to length, intron height reflects the number of cDNAs supporting each intron, the small numbers show the support of the introns in deep sequencing (with details in mouse-over) . Introns of the same color are identical, of different colors are different. 'Good proteins' are pink, partial or not-good proteins are yellow, uORFs are green. 5' cap or3' poly A flags show completeness of the transcript.
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