9.B.464.  The Possible Glycosylase Crh2 (Crh2) Family  

Crh2 is of 467 aas with 2 TMSs, one N-terminal and one C-terminal.  As a consequence of hypoosmotic shock, yeast cells swell rapidly and increase the surface area by ∼20% in 20 seconds (Smith et al. 2024). Approximately, 35% of this surface increase is mediated by the ER-plasma membrane contact sites, specifically via the tricalbins (see TC# Family 9.B.454), which are required for the delivery of both lipids and the GPI-anchored protein Crh2 from the cortical ER to the plasma membrane. Therefore, it was proposed that a new function for the tricalbins involves mediating the fusion of the ER to the plasma membrane at contact sites. This proposed fusion is triggered by calcium influx via the stretch-gated channel Cch1 (TC# 1.A.1.11.10) and is supported by the anoctamin Ist2 (TC# 1.A.17.1.19).