I am not convinced that DMT requires a transporter especially a specific one.  Freebasing or injecting a drug (or smoking a low bp drug) in most cases leads to rapid effects.  We would thus have to assume that drugs like cocaine, THC, JWH-018, opiates, amphetamines, ... all have transport mechanisms.  While they may they are probably then non-specific or it is just that the drugs are all lipid soluble even when protonated for enough to cross the BBB is significant quantities to induce rapid pharmacological effects.  Maybe a combination of both?