8.A.41 The Stretch-activated Calcium Channel Auxiliary Protein, Mid1 (Mid1) Family The Mid1 protein in Saccharomyces cerevisiae forms a complex with the Cch1 calcium channel (TC# 1.A.1.11.10) and the Ecm7 protein (TC# 1.H.1.4.6). The Mid1 protein appears to be essentially required for activity of Cch1 which is homologous to VIC family alpha subunits. Mid1 proteins always have an N-terminal TMS, sometimes have a C-terminal TMS, and have been reported to have as many as 4 TMSs. The Ecm7 protein is a homologue of claudins, some of which have been reported to have channel activity.
References:
Bormann, J. and P. Tudzynski. (2009). Deletion of Mid1, a putative stretch-activated calcium channel in Claviceps purpurea, affects vegetative growth, cell wall synthesis and virulence. Microbiology 155: 3922-3933.
Cavinder, B., A. Hamam, R.R. Lew, and F. Trail. (2011). Mid1, a mechanosensitive calcium ion channel, affects growth, development, and ascospore discharge in the filamentous fungus Gibberella zeae. Eukaryot. Cell. 10: 832-841.
Lew, R.R., Z. Abbas, M.I. Anderca, and S.J. Free. (2008). Phenotype of a mechanosensitive channel mutant, mid-1, in a filamentous fungus, Neurospora crassa. Eukaryot. Cell. 7: 647-655.
Liu, M. and A. Gelli. (2008). Elongation factor 3, EF3, associates with the calcium channel Cch1 and targets Cch1 to the plasma membrane in Cryptococcus neoformans. Eukaryot. Cell. 7: 1118-1126.
Examples:
TC#	Name	Organismal Type	Example
8.A.41.1.1	Mid1 auxiliary subunit of strech-activated calcium channel, Cch1 (TC# 1.A.1.11.10).	Yeast	Mid1 of Saccharomyes cerevisiae

8.A.41.1.2	Mid1 auxiliary protein with Cch1 (Liu and Gelli 2008).	Fungi	Mid1 of Cryptococcus neoformans

8.A.41.1.3	Mid1 of 558 aas	Fungi	Mid1 of Candida albicans

8.A.41.1.4	*Mid1 of 618 aas. Homologous to the α2δ subunit of mammalian VIC calcium channels. Required for ascospore development (Cavinder et al.* 2011).**	Fungi	*Mid1 of Gibberella zeae* (Wheat head blight fungus) (Fusarium graminearum)**

8.A.41.1.5	Mid1 of 653 aas. Required for virulence on rye (Bormann and Tudzynski 2009).	Fungi	Mid1 of Claviceps purpurea

8.A.41.1.6	*Mid1 component of the Ca²⁺ uptake system, Cch1/Mid1 in filamentous fungi. Required for high affinity calcium uptake and homeostasis but not for conidiation (Lew et al.* 2008).**	Fungi	Mid1 of Neurospora crassa

8.A.41.1.7	*Mid1 component of fission yeast Cch1/Mid1 (Yam8) Ca²⁺ channel complex (Ma et al., 2011).*	Yeast	Cch1/Mid1 of Schizosaccharomyces pombe Cch1 (O14234) Mid1 (Q10063)

8.A.41.1.8	Stretch-activated cation channel, putative (Component of the high affinity calcium uptake system) of 561 aas	Fungi	Calcium channel of Candida bubliniensis