Pleckstrin homology-like domain, repeat 2, of Histone chaperone RTT106 (regulator of Ty1 transposition protein 106)
Rtt106 is a histone chaperone. Rtt106 contains an N-terminal homodimerization domain and two C-terminal pleckstrin-homology (PH) domains (PH1 and PH2). The binding of Rtt106 to H3K56-acetylated (H3-H4)2 tetramers contributes to nucleosome assembly in terms of DNA replication, gene silencing and maintenance of genomic stability. The N-terminal domain homodimerizes homodimerizes and interacts with H3-H4 independently of acetylation while the double PH domain binds the K56-containing region of H3. Rtt106 also interacts with both the SWI/SNF and RSC chromatin remodeling complexes and is involved in their cell-cycle dependent recruitment to histone gene pairs regulated by the HIR co-repressor complex (HTA1-HTB1, HHT1-HHF1, and HHT2-HHF2). This model contains the second PH-like domain repeat. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.
Jiyao W et al.(2023). "The conserved domain database in 2023.",