Table 4.
Comparative analysis of yeast ENV7 and its mammalian ortholog, STK16
| Characteristic | STK16/MPSK/PKL12/KRCT/TGF-β-stimulated factor 1 | YPL236C/ENV7 |
|---|---|---|
| Cell type | Mammalian | S. cerevisiae |
| Cellular localization | Golgi apparatus (71) | Vacuolar membrane (29 and this study) |
| Cellular function | Not established | Negatively regulates vacuolar membrane fusion (this study) |
| Peptide length | 305 aa (72) | 364 aa (this study) |
| Lipid modification | N-terminal myristoylation and palmitoylation | Palmitoylation (this study) |
| Enzymatic activity | Kinase (72–76) | Kinase (this study) |
| Autophosphorylation | Yes (72, 76, 77) | Yes (this study) |
| Cation specificity | Mg2+ (51) | Mg2+ (this study) |
| Exogenous substrates | H1, MBP (76), PHAS-I (72), enolase (51), Elk1 activation domain (75) | β-Casein, MBP, H1, H3, H2A (this study) |
| Kinase-dead allele | E202A of APE motif (71) | C13-15S, E269A of APE motif (this study) |
| Structural motifs | ||
| Glycine-rich loop (GXGXXG/Ψ)a | GEGGFSY (aa 27–33) | GEGGMSF (aa 37–43) |
| DFG motifb | DLG | DLG |
| Activation loop | APE | PPE |
a
The glycine-rich loop (GXGXXG/Ψ) is a universally conserved region of protein kinases involved in nucleotide binding, substrate recognition, and catalysis (70).
b
The phenylalanine residue of the DFG motif is well conserved in protein kinases and serves as part of the enzyme's hydrophobic spine (78).