<P> Weak bases with lipophilic properties accumulate in acidic intracellular compartments like lysosomes . While the plasma and lysosomal membranes are permeable for neutral and uncharged species of weak bases, the charged protonated species of weak bases do not permeate biomembranes and accumulate within lysosomes . The concentration within lysosomes may reach levels 100 to 1000 fold higher than extracellular concentrations . This phenomenon is called "lysosomotropism", "acid trapping" or "proton pump" effect . The amount of accumulation of lysosomotropic compounds may be estimated using a cell - based mathematical model . </P> <P> A significant part of the clinically approved drugs are lipophilic weak bases with lysosomotropic properties . This explains a number of pharmacological properties of these drugs, such as high tissue - to - blood concentration gradients or long tissue elimination half - lifes; these properties have been found for drugs such as haloperidol, levomepromazine, and amantadine . However, high tissue concentrations and long elimination half - lives are explained also by lipophilicity and absorption of drugs to fatty tissue structures . Important lysosomal enzymes, such as acid sphingomyelinase, may be inhibited by lysosomally accumulated drugs . Such compounds are termed FIASMAs (functional inhibitor of acid sphingomyelinase) and include for example fluoxetine, sertraline, or amitriptyline . </P> <P> Ambroxol is a lysosomotropic drug of clinical use to treat conditions of productive cough for its mucolytic action . Ambroxol triggers the exocytosis of lysosomes via neutralization of lysosomal pH and calcium release from acidic calcium stores . Presumably for this reason, Ambroxol was also found to improve cellular function in some disease of lysosomal origin such as Parkinson's or lysosomal storage disease . </P> <P> By scientific convention, the term lysosome is applied to these vesicular organelles only in animals, and the term vacuole is applied to those in plants, fungi and algae (some animal cells also have vacuoles). Discoveries in plant cells since the 1970s started to challenge this definition . Plant vacuoles are found to be much more diverse in structure and function than previously thought . Some vacuoles contain their own hydrolytic enzymes and perform the classic lysosomal activity, which is autophagy . These vacuoles are therefore seen as fulfilling the role of the animal lysosome . Based on de Duve's description that "only when considered as part of a system involved directly or indirectly in intracellular digestion does the term lysosome describe a physiological unit", some botanists strongly argued that these vacuoles are lysosomes . However, this is not universally accepted as the vacuoles are strictly not similar to lysosomes, such as in their specific enzymes and lack of phagocytic functions . Vacuoles do not have catabolic activity and do not undergo exocytosis as lysosomes do . </P>

Which of the following is not a function of lysomes