Table 1.
Proteins required for mRNA localization in yeast. Listed are proteins with a likely direct function in ASH1 mRNA localization. Excluded are proteins required for general cellular functions. Core components of the ASH1 mRNP are defined by a complete loss of ASH1 mRNA localization upon their genomic deletion
| Protein | Subcellular localization | Protein domain(s) | Core mRNP component? | Protein function | Defect upon mutation |
|---|---|---|---|---|---|
| She2p | Nucleus and cytoplasm | Unique | Yes | Cotranscriptional binding of localizing mRNAs and synergistic cytoplasmic recognition of transcripts with She3p; binds to zip-code elements and localizing mRNAs | Complete loss of mRNA localization |
| She3p | Cytoplasm | No known homology | Yes | Myosin-adapter and RNA-binding protein; acts synergistically with She2p for specific recognition of zip-code elements and localizing mRNAs; required for ER inheritance | Complete loss of mRNA localization |
| Myo4p/She1p | Cytoplasm | Type V myosin with myosin motor domain, IQ motifs, coiled-coil, and C-terminal cargo-binding domain | Yes | Motor protein; interacts with She3p and provides motile activity along actin filaments for mRNA and ER transport into the daughter cell | Complete loss of mRNA localization |
| She4p | Cytoplasm | UCS domain | Unclear | Binds to myosin motor domains and might regulate their function | Complete loss of mRNA localization |
| Puf6p | Mainly nuclear and nucleolar; some in cytoplasm | Seven pumilio-like repeats and CPL domain | No | Translational repression during mRNA transport to bud tip; binds to UUGU consensus motif | Reduced mRNA localization; premature translation |
| Khd1p | Nucleus and cytoplasm | Three K-homology domains | No | Translational repression during mRNA transport to bud tip; binds to CNN repeats and to the E1 element of ASH1 mRNA | Mildly reduced mRNA localization; premature translation |
| Loc1p | Nucleus, enriched in nucleolus | No known homology | No | Required for ASH1 mRNA localization and ribosome biogenesis; molecular function is unknown; binds to the E3 element of ASH1 mRNA and to double-stranded RNAs | Reduced mRNA localization; premature translation |
| Scp160 | Cytoplasm | Six K-homology domains | No | RNA-binding protein involved in telomere silencing and correct ASH1 mRNA localization; exact role in ASH1 mRNA localization is unknown | Reduced mRNA localization |
| Mtp5/Puf5p | Cytoplasm | Seven pumilio-like repeats | No | RNA-binding protein involved in longevity, cell wall integrity, mRNA degradation, and ASH1 mRNA localization; exact role in ASH1 mRNA localization is unknown | Reduced mRNA localization |