Figure: septation initiation signaling (GO:0031028)¶
This figure illustrates the Septation Initiation Signaling (SIN) pathway in Schizosaccharomyces pombe, which regulates cytokinesis by coordinating the assembly and constriction of the actomyosin ring with nuclear division.
At the core of SIN signaling are two spindle pole bodies (SPBs): the old SPB (GO:0071957) and new SPB (GO:0071958), which serve as scaffolds for the signaling proteins. Scaffold proteins Sid4 and Cdc11 anchor other SIN components to the SPB.
The GTPase module consists of Spg1 (a small GTPase), regulated by the bipartite GAP complex Byr4-Cdc16, which inhibits SIN signaling. The Dma1 ubiquitin ligase negatively regulates SIN by interfering with Plo1 activity.
On the new SPB, the kinase module activates in sequence: Cdc7 binds to Spg1-GTP, followed by Sid1-Cdc14 complex activation. This leads to activation of the Sid2-Mob1 complex (GO:0034973), which translocates to the actomyosin ring to trigger septation.
Regulatory proteins include phosphatases (Ppa3, Clp1) and kinases (Fin1), along with other modulators (Etd1, Ypa2, Dnt1), which fine-tune the timing and spatial regulation of septation.
The CSC complex (Csc1-4) contributes to negative regulation of SIN signaling by promoting Ppa3 phosphatase activity.
Color coding indicates protein functions: blue for scaffold proteins, orange for GTPases, light blue for kinases, and pink for regulatory proteins.
Feedback from AI on figure:
{"feedback":"The drawing effectively illustrates the septation initiation signaling pathway in S. pombe, with clear organization of the key components and their interactions. The color-coded proteins and complexes help distinguish between different functional groups (scaffold proteins, GTPases, kinases, and regulatory proteins), while the directional arrows clearly indicate activation or inhibitory relationships. The diagram accurately represents the subcellular organization with old and new spindle pole bodies properly positioned and the actomyosin contractile ring at the cell division site. The expanded legend provides helpful context about protein functions and relationships without overcrowding the diagram itself.","necessary_changes":null,"optional_changes":null}