High impact information on SIP2

• Green fluorescent protein fusions to Gal83, Sip1, and Sip2 show different patterns of localization to the nucleus, vacuole, and/or cytoplasm [1].
• Sip2p and its partner snf1p kinase affect aging in S. cerevisiae [2].
• Previous studies showed that the Sip1/Sip2/Gal83 component plays a structural role in the complex [3].
• Evidence indicates that Sip1 and Sip2 do not interact with Sip4 [3].
• When plasma membrane association of Sip2p is abolished by a mutation that blocks its N-myristoylation, Snf4p is shifted to the nucleus [4].

Biological context of SIP2

• The rapid-aging phenotype of sip2 Delta cells is fully rescued by blocking recombination at rDNA loci with a fob1 Delta allele; rescue is not accompanied by amelioration of an age-associated shift toward gluconeogenesis and glucose storage [4].
• DNA sequence analysis revealed that they were orthologues of the yeast GAL83/SIP1/SIP2 genes and their mammalian counterparts, AMPK beta-subunits [5].
• The amino acid sequence of the beta subunit is most closely related to SIP2 (35% identity), while the amino acid sequence of the gamma subunit is 35% identical with SNF4 [6].
• The 5' end matches the previously described gene, VAM7, and the 3' end matches the previously described gene, SPM2, both of which have been assigned to the left arm of chromosome VII [7].

Anatomical context of SIP2

• Rapidly aging sip2 Delta cells have higher levels of histone H3 kinase activity than their generation-matched isogenic wild type counterparts [4].

Associations of SIP2 with chemical compounds

• High-copy clones of SIP1 and SIP2 cross-complement the GAL83-2000 mutation (as well as GAL82-1, a mutation in another gene involved in glucose repression), suggesting that these four genes may perform similar functions in glucose repression [8].
• Covalent attachment of myristate to the N-terminal Gly of Sip2p is essential for normal cellular life span [4].

Physical interactions of SIP2

• In mammalian cells, alpha1-Snf1 yielded a functional kinase complex following co-expression with the yeast regulatory subunits Sip2 and Snf4 [9].
• We propose that members of the Sip1/Sip2/Gal83 family confer specificity to the kinase complex in its interactions with target proteins [3].
• We recovered Yap1 in a two-hybrid screen for proteins that interact with the Sip2 subunit of the Snf1 protein kinase, which is required for the adaptation of cells to glucose limitation [10].

Other interactions of SIP2

• Sip2, an N-myristoylated beta subunit of Snf1 kinase, regulates aging in Saccharomyces cerevisiae by affecting cellular histone kinase activity, recombination at rDNA loci, and silencing [4].
• Saccharomyces cerevisiae encodes three beta-subunit genes, SIP1, SIP2 and GAL83 [11].
• This ORF also has a striking similarity to a putative 43 kDa zinc finger protein encoded by an ORF (YEL8) immediately downstream of YPT8, raising the possibility that a region between VAM7 and SPM2 on chromosome VII arose as a duplication of the YPT8-YEL8 region of chromosome V, followed by a translocation [7].

References