1.A.55 The Synaptic Vesicle-Associated Ca2+ Channel, Flower (Flower) Family

Synaptic vesicle (SV) exo- and endocytosis are tightly coupled to sustain neurotransmission in presynaptic terminals, and both are regulated by Ca2+. Ca2+ influx triggered by voltage-gated Ca2+ channels is necessary for SV fusion. However, extracellular Ca2+ has also been shown to be required for endocytosis. The intracellular Ca2+ levels (<1 μM) that trigger endocytosis are typically much lower than those (>10 μM) needed to induce exocytosis, and endocytosis is inhibited when the Ca2+ level exceeds 1 μM.  Yao et al., (2009) identified and characterized a 4 TMS transmembrane protein named 'Flower', associated with SVs that, upon SV fusion, localizes at periactive zones. Loss of Flower results in impaired intracellular resting Ca2+ levels and impaired endocytosis. Flower multimerizes and is able to form a channel to control Ca2+ influx. Yao et al. (2009) proposed that Flower functions as a Ca2+ channel to regulate synaptic endocytosis and hence couples exo- with endocytosis. Homologues may be present in various intrarcellular membranes.  The Flower family is also called the Cg6252-P Family.



This family belongs to the .

 

References:

Yao, C.K., Y.Q. Lin, C.V. Ly, T. Ohyama, C.M. Haueter, V.Y. Moiseenkova-Bell, T.G. Wensel, and H.J. Bellen. (2009). A synaptic vesicle-associated Ca2+ channel promotes endocytosis and couples exocytosis to endocytosis. Cell 138: 947-960.

Examples:

TC#NameOrganismal TypeExample
1.A.55.1.1

Mammalian Ca2+ channel, Flower, homologue, isoform a (Yao et al., 2009).

Animals

Flower of Homo sapiens (Q9UGQ2)

 
1.A.55.1.2

Insect Ca2+ channel, Flower (194 aas; 4 putative TMSs)

Animals

Flower of Drosophila melanogaster (Q95T12)

 
1.A.55.1.3

Roundworm Flower homologue (166aas)

Animals

Flower homologue of Caenorhabditis elegans (Q93533)

 
Examples:

TC#NameOrganismal TypeExample
1.A.55.2.2

Flower homologue of 175 aas and 3 putative TMSs

Ichthyosporea

Flower homologue of Capsaspora owczarzaki

 
1.A.55.2.3

Flower homologue of 193 aas

Choanoflagellida

Fower homologue of Salpingoeca rosetta

 
Examples:

TC#NameOrganismal TypeExample
1.A.55.3.1

Flatworm Flower homologue (195aas)

Animals

Flower homologue of Schistosoma japonicum (Q5DFV8)

 
Examples:

TC#NameOrganismal TypeExample
1.A.55.4.1

Fungal flower homologue (149aas)

Fungi

Flower homologue of Aspergillus flavus (B8N1Q6)

 
1.A.55.4.2

The yeast Tvp18p protein of 102 aas and 2 TMSs.

Fungi

Tvp180 of Saccharomyces cerevisiae

 
1.A.55.4.3

Uncharacterized protein of 127 aas and 4 TMSs

Stramenopiles

UP of Blastocystis hominis

 
Examples:

TC#NameOrganismal TypeExample
1.A.55.5.1

Uncharacterized protein of 151 aas and 3-4 putative TMSs.

Stramenopiles

UP of Ectocarpus siliculosus (Brown alga)

 
Examples:

TC#NameOrganismal TypeExample
1.A.55.6.1

Uncharacterized protein of 176 aas and 3 TMSs

Slime molds

UP of Dictyostelium fasciculatum 

 
1.A.55.6.2

Uncharacterized protein of 154 aas and 3 TMSs

Slime molds

UP of Dictyostelium discoideum