8.A.175. The Vasculature Complexity and Connectivity (VCC) Family Arabidopsis VASCULATURE COMPLEXITY AND CONNECTIVITY (VCC) is a plant-specific transmembrane protein that controls the development of veins in cotyledons. Yanagisawa et al. 2021 showed that the expression and localization of PIN1 (TC# 2.A.69.1.1) is altered in vcc developing cotyledons, and that overexpression of PIN1-GFP partially rescues the vascular defects of vcc mutants. Genetic analyses suggested that VCC and PINOID (PID), a kinase that regulates PIN1 polarity, are both required for PIN1-mediated control of vasculature development. VCC expression is upregulated by auxin, likely as part of a positive feedback loop for the progression of vascular development. VCC and PIN1 localized to the plasma membrane in pre-procambial cells but were actively redirected to vacuoles in procambial cells for degradation. In the vcc mutant, PIN1 failed to properly polarize in pre-procambial cells during the formation of basal strands, and instead, it was prematurely degraded in vacuoles. VCC plays a role in the localization and stability of PIN1, which is crucial for the transition of pre-procambial cells into procambial cells that are involved in the formation of basal lateral strands in embryonic cotyledons (Yanagisawa et al. 2021).
References:
Sun, Y., T. Deng, A. Zhang, M.J. Moore, J.B. Landis, N. Lin, H. Zhang, X. Zhang, J. Huang, X. Zhang, H. Sun, and H. Wang. (2020). Genome Sequencing of the Endangered Kingdonia uniflora (Circaeasteraceae, Ranunculales) Reveals Potential Mechanisms of Evolutionary Specialization. iScience 23: 101124.
Yanagisawa, M., A. Poitout, and M.S. Otegui. (2021). Arabidopsis vascular complexity and connectivity controls PIN-FORMED1 dynamics and lateral vein patterning during embryogenesis. Development 148:.
Examples:
TC#	Name	Organismal Type	Example
8.A.175.1.1	*VASCULATURE COMPLEXITY AND CONNECTIVITY (VCC) protein of 163 aas and 4 TMSs in a 1 + 3 TMS arrangement. See family description for details (Yanagisawa et al.* 2021).**		*VCC of Arabidopsis thaliana* (Mouse-ear cress)**

8.A.175.1.2	Uncharacterized protein of 177 aas and 4 TMSs in a 1 + 2 + 1 TMS arrangement.		UP of Cannabis sativa

Examples:
TC#	Name	Organismal Type	Example
8.A.175.2.1	*Uncharacterized DUF1218 protein of 262 aas and 5 TMSs in a 1 + 4 TMS arrangement (Sun et al.* 2020).**		*UP of Kingdonia uniflora* (Circaeasteraceae, Ranunculales)**

8.A.175.2.2	Uncharacterized protein of 245 aas and 5 TMSs in a 2 + 2 + 1 TMS arrangement.		UP of Dendrobium chrysotoxum

8.A.175.2.3	Uncharacterized protein of 186 aas and 4 TMSs.		UP of Aquilegia coerulea

8.A.175.2.4	Uncharacterized protein of 262 aas and 4 TMSs.		UP of Carya illinoinensis

8.A.175.2.5	Uncharacterized protein of 160 aas and 4 TMSs.		*UP of Aegilops tauschii* subsp. strangulata**