Secreted acid phosphatase

Ascencio, J. (1997) Root-secreted acid phosphatase kinetics as a physiological marker for phosphorus deficiency, youma/ of Plant Nutrition 20, 9-26. 

Ilg T, Overath P, Ferguson MA et al. O- and N- ycosylation of the Leishmania mesicana-secreted acid phosphatase Characterization of a new class of phosphoserine-linked ycans. J Biol Chem 1994 269 24073-24081. 

Provenge (sipuleucel T) is a prostate cancer vaccine made from antigen-presenting cells from the patient s own immune system, which are fused to a protein (prostate-secreted acid phosphatase) made from prostate cells. It is currently being evaluated in phase III trials. 

The adult male prostate contains abundant acid phosphatase which it secretes into the semen. The production of this enzyme is governed by the circulating levels of androgenic hormones. Castration or estrogen administration markedly reduces the prostatic urinary acid phosphatase of males. Other organs such as the liver, kidney, spleen, red cells and platelets also contain significant amounts of acid phosphatase. 

In soil, the chances that any enzyme will retain its activity are very slim indeed, because inactivation can occur by denaturation, microbial degradation, and sorption (61,62), although it is possible that sorption may protect an enzyme from microbial degradation or chemical hydrolysis and retain its activity. The nature of most enzymes, particularly size and charge characteristics, is such that they would have very low mobility in soils, so that if a secreted enzyme is to have any effect, it must operate close to the point of secretion and its substrate must be able to diffuse to the enzyme. Secretory acid phosphatase was found to be produced in response to P-deficiency stress by epidermal cells of the main tap roots of white lupin and in the cell walls and intercellular spaces of lateral roots (63). Such apoplastic phosphatase is safe from soil but can be effective only when presented with soluble organophosphates, which are often present in the soil. solution (64). However, because the phosphatase activity in the rhizo-sphere originates from a number of sources (65), mostly microbial, and is much higher in the rhizosphere than in bulk soil (66), it seems curious that plants would have a need to secrete phosphatase at all. 

H. Sakai and T. Tadano, Characteristics of respon.se of acid phosphatase secreted by the roots of several crops to various conditions in the growth media. Soil Sci. Plant Nutr. 39 431 (1993). 

Lavallee and Rosenkrantz (54) studied the purification of dog prostatic acid phosphatase from prostatic secretion obtained from pilocarpine-stimulated dogs with cystopreputiostomy prostatic fistulas. A 45-... 

S10. Schuurmans, A. L., Bolt, J., Veldscholte, J., and Mulder, E., Stimulatory effects of antiandrogens on LNCaP human prostate tumor cell growth, EGF-receptor level and acid phosphatase secretion. J. Steroid Biochem. Mol. Biol. 37, 849-853 (1990). 

In man and in other mammalian species, the major mass of the prostate, usually consisting of the right and left lateral and the middle lobes, is composed of alveoli lined with columnar epithelium embedded in a thick fibromuscular stroma. These alveoli constantly secrete a fluid which is drained off by a system of branching ducts that empty into the floor and lateral surfaces of the posterior urethra. The normal secretion is dependent upon the degree of androgenic stimulation and amounts to about 0.5-2 ml per day. The prostatic secretion, which is characterized by very high acid phosphatase activity, is a milky fluid which contains citric acid, choline, cephalin, cholesterol, proteins, and electrolytes similar to those found in the plasma. 

Attempts to determine the intracellular distribution of acid phosphatase in the prostate must take into account the presence of this enzyme in the extracellular secretion. Employing centrifugal methods, Siebert et al. (S20) found that of the total acid phosphatase present in bull prostate homogenate, 0.7% was in the nuclear fraction, 41% in the mitochondrial fraction which presumably included the lysosomal component, and 84% in the microsomal and supernatant components. The finding that the sum of these activities exceeded that in the homogenate was considered to represent removal of inhibitors during separation of the fractions. 

Clark and Treichler (04) have studied the psychic factors involved in prostatic secretion, and it is possible that physiological or psychological stimuli might have played a role in yielding high values for prostatic acid phosphatase activity on the first visit. These patients were followed for a period of 6 months to a year and no evidence arose which indicated that these elevations had any pathological significance (D6). 

Although the fibromuscular structure of the prostate has some acid phosphatase activity, histochemical studies reveal that most of the activity is present in the epithelial cells of the secreting glands (Rla). In carcinoma of the prostate, the staining of the epithelial cells for acid phosphatase show greater variation. The staining may be less, equal to, or greater than in the normal prostate (Rla). 

During bone resorption, osteoclasts produce and secrete an acid phosphatase. The activity of this TRAP has been measured using a number of methods. Unfortunately, most methods failed to distinguish between the osteclastic TRAP (isoform 5b) and other TRAPs (isoform 5a) found in plasma." In addition, instability of the enzyme and association of the enzyme with a2-macroglulin have complicated... 

Scott, W. W., and Huggins, C., The acid phosphatase activity of human urine, an index of prostatic secretion. Endocrinology 30, 107-120 (1942). 

In 2007 we characterized a novel transmembrane type-I isoform of the prostatic acid phosphatase enzyme (TMPAP) as the product of a splice variant of the same gene encoding the secreted form (sPAP). This transmembrane type-I isoform contains a tyrosine-based lysosomal targeting (YxxO) motif at the... 

In vitro studies have shown that TRAcP 5b isoform remains intracellularly in macrophages and dendritic cells which only secrete the TRAcP 5a isoform [25]. Therefore, for clinical determinations it is assumed that the tartrate-resistant acid phosphatase activity associated with bone resorbing osteoclasts derives only from the TRAcP 5 b isoform. 

Acid phosphatase, prostate ACPP 55 Prostatic acid phosphatase PAP, sPAP (secreted isoform), TMPAP (transmembrane isoform), ACP3... 

Vihko P, Kurkela R, Porvari K et al (1993) Rat acid phosphatase overexpression of active, secreted enzyme by recombinant baculovirus-infected insect cells, molecular properties, and crystallization. Proc Natl Acad Sci USA 90 799-803... 

Tumour markers fall into one of several groups they may be homiones. e.g. human chorionic gonadotrophin (HCG) secreted by choriocarcinoma or enzymes, e.g. prostatic acid phosphatase in prostate carcinoma or tumour antigens. e.g. carcinoembryonic antigen (CEA) in colorectal carcinoma. 

The major difference between the secreted and membrane-bound acid phosphatase is that the latter is approximately 40-fold more resistant to the inhibitory effects of sodium tartrate. Furthermore, non-specific antibodies to the extracellular enzyme do not cross-react with membrane-bound enzyme. The secreted enzyme also does not appear to inhibit neutrophil oxidative burst, unlike its membranous counterpart. The biological role of the secreted enzyme is unknown, but may be involved in modification of host activities. 

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