2.A.1.2.104
MFS carrier of 490 aas and 12 TMSs, MfsD14a or Hiat1 (Hippocampus abundant transcript 1 protein) is a member of the SLC18 family.  It is 76% identical to 2.A.1.2.30. Mutant mice (Mus musculus, strain 129S6Sv/Ev) were generated with the Mfsd14a gene disrupted with a LacZ reporter gene. Mutant mice are viable and healthy, but males are sterile due to a 100-fold reduction in the number of spermatozoa in the vas deferens. Male mice have adequate levels of testosterone and show normal copulatory behaviour. The few spermatozoa that are formed show rounded head defects similar to those found in humans with globozoospermia. Spermatogenesis proceeds normally up to the round spermatid stage, but the subsequent structural changes associated with spermiogenesis are severely disrupted with failure of acrosome formation, sperm head condensation and mitochondrial localization to the mid-piece of the sperm. Mfsd14a expression occurs in Sertoli cells, suggesting that MFSD14A may transport a solute from the bloodstream that is required for spermiogenesis (Doran et al. 2016). MFSD14A and MFSD14B are intracellular neuronal membrane-bound proteins, expressed in the Golgi and ER, and their levels of expression are affected by both starvation and a high fat diet to varying degrees in the mouse brain (Lekholm et al. 2017). It is associated with milk production in buffalo and sheep breeds, as well as growth of chickens and goats, and drastically affect s sperm morphogenesis (Luo et al. 2023). The functional InDel polymorphism (rs1089950828) reflects growth traits in domestic sheep populations (Luo et al. 2023).