Phosphorylation of ribosomal proteins by ribosome‐associated protein kinases of Trichosporon cutaneum

Abstract

Four ribosomal proteins of Mr 13 kDa, 15 kDa, 19 kDa and 38 kDa were identified as phosphorylation substrates for protein kinases tightly associated with Trichosporon cutaneum ribosomes. It was found that proteins of 13 kDa, 19 kDa and 38 kDa were phosphorylated by multifunctional casein kinase II while the protein of 15 kDa by casein kinase I. Proteins of 13 kDa and 38 kDa were detected in the large subunits while 15 kDa and 19 kDa in the small ribosomal subunits. By using isoelectrofocusing the protein of 13 kDa was resolved into two individual phosphorylated forms. The phosphorylation level of both forms was much higher in ribosomes from the cells collected at the exponential growth phase than in those from the stationary phase. The same phosphoprotein forms were identified in ribosomes from in vitro and in vivo [32P]-labelling experiments.

The effect of heparin on the activity of Trichosporon cutaneum casein kinase I

“…It is known from our recent studies that CKI tightly associated with 80s ribosomes T. cutaneum phosphorylated protein of 15 kDa which is a member of small ribosomal subunit ( WOJDA et al 1996). As can be seen on Fig.…”

“…It can phosphorylate cytoskeletal proteins such as myosin, ankyrin, troponin, spectrin and neural filament proteins; nuclear proteins such as p53, CAMP response element modulator (CREM), RNA polymerases I and 11, SV 40 large T antigen; metabolic enzymes such as glycogen synthase and acetyl CoA carboxylase and proteins involved in mRNA translation such as initiation factors 3, 4B, 4E and 5, aminoacyl-tRNA synthetases etc. (GRANKOWSKI and ISSINGER 1990, TUAZON and TRAUGH 1991.Our recent studies performed on Trichosporon cutaneum allowed to show that protein of 15 m a , a member of small ribosomal subunit, is modified by CKI both in vitro and in vivo (WOJDA et al 1996). There are not much data available concerning the control of CKI activity.…”

“…Our recent studies performed on Trichosporon cutaneum allowed to show that protein of 15 m a , a member of small ribosomal subunit, is modified by CKI both in vitro and in vivo (WOJDA et al 1996). There are not much data available concerning the control of CKI activity.…”

Protein kinases CKI and CKII are implicated in modification of ribosomal proteins of the yeast Trichosporon cutaneum.

“…We have found that in Trichosporon cutaneum, unlike in other yeast species, besides the P-proteins, two additional ribosomal proteins of molecular mass 15 kDa and 19 kDa, were phosphorylated both in vivo and in vitro. These proteins do not belong to the acidic ribosomal protein family and were identified on the small ribosomal subunit (Wojda et al, 1996).…”

“…It can phosphorylate many cytoskeletal and nuclear proteins, metabolic enzymes and proteins involved in mRNA translation (Grankowski & Issinger, 1990;Tuazon & Traugh, 1991;Vancura et al, 1994). The protein of 15 kDa of the yeast T. cutaneum is the only known ribosomal protein substrate for CKI (Wojda et al, 1996). In this paper we describe protein kinases: CKI and CKII, which are implicated in the modification of T. cutaneum ribosomal proteins.…”