number of abnormalities of premelanosomes and melanosomes. Few premelanosomes were present. Most of the melanin granules were giant sized, but their structures varied. Some of the giant granules were composed of several premelanosomes and melanosomes in different stages of maturation. Others contained randomly oriented melanofilaments between melanosomes. There were also complex giant granules consisting of both melanosomal and lysosomal components. Inappropriate fusion of cytoplasmic granules appears to be the most likely mechanism for formation of the giant granules. Fusion of premelanosomes with lysosomes and resultant destruction of the premelanosomes probably is a major cause of the ocular hypopigmentation of Chediak-Higashi syndrome." Hargis AM, Prieur DJ. Animal model: renal lesions in cats with Chediak-Higashi-Steinbrinck syndrome. Am J Med Genet. 1987 Jan;26(1):169-79. "In this study designed to characterize
studies indicate lysosomes are prevalent in Discovered about a decade after cathepsins fetal muscle tissue but occur much less fre- (Guroff 1964), calpains have been exten- quently in adult skeletal muscle. Cathepsins sively researched and the subject of many are distinguished by their active sites (aspar- reviews on muscle proteolysis (Goll et al. tic, cysteine, and serine proteases) and 1992, 1998, 2003; Geesink et al. 2000; Ilian substrate specificity. Over 15 lysosomal et al. 2001; Friedrich and Bozóky 2005; cathepsins have been identified, but only Geesink et al. 2005; Koohmaraie and Geesink eight (B, L, H, S, F, K, D, E) have been found 2006; Geesink and Veiseth 2009). Currently, in skeletal muscle fibers (Barnier 1995; at least 15 different calpains have been iden- Hopkins and Thompson 2002; Sentandreu et tified in mammals (Suzuki et al. 2004). Six al. 2002)
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