As a new technology for next-generation vehicle-to-everything (V2X) communication, visible-light communication (VLC) using light-emitting diode (LED) transmitters and camera receivers has been energetically studied. Toward the future in which vehicles are connected anytime and anywhere by optical signals, the cutting-edge camera receiver employing a special CMOS image sensor, i.e., the optical communication image sensor (OCI), has been prototyped, and an optical V2V communication system applying this OCI-based camera receiver has already demonstrated 10-Mb/s optical signal transmission between real vehicles during outside driving. In this paper, to reach a transmission performance of 54 Mb/s, which is standardized as the maximum data rate in IEEE 802.11p for V2X communication, a more advanced OCI-based automotive VLC system is described. By introducing optical orthogonal frequency-division multiplexing (optical-OFDM), the new system achieves a more than fivefold higher data rate. Additionally, the frequency response characteristics and circuit noise of the OCI are closely analyzed and taken into account in the signal design. Furthermore, the forward-current limitation of an actual LED is also considered for long operational reliability, i.e., the LED is not operated in overdrive. Bit-error-rate experiments verify a system performance of 45 Mb/s without bit errors and 55 Mb/s with BER G 10 À5 .Index Terms: Visible light communication (VLC), intelligent transport system (ITS), vehicleto-vehicle (V2V) communication, infrastructure-to-vehicle (I2V) communication, light-emitting diode (LED), image sensor-based VLC, optical communication image sensor (OCI), optical orthogonal frequency division multiplexing (optical-OFDM).

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Protein glycosylation, one of the post-translational modifications, is important for many protein functions, such as protein stability, folding and secretion. In the protein glycosylation, C-mannosylation was first identified in ribonuclease 2, and some proteins have been reported to be C-mannosylated; however, effects of its modifications for target proteins remain unclear. Hyaluronidase 1 (HYAL1), degrading hyaluronic acid (HA), has two predicted C-mannosylation sites at Trp¹³⁰ and Trp³²¹. In this study, we examined whether HYAL1 is C-mannosylated or not, and the effect of C-mannosylation on HYAL1. Using mass spectrometry, we first demonstrated that intracellular HYAL1 is C-mannosylated at Trp¹³⁰ but not at Trp³²¹. Surprisingly, although HYAL1 was secreted into conditioned medium and it possessed enzymatic activity, secreted HYAL1 was not C-mannosylated. Computer simulation demonstrated that C-mannosylation of HYAL1 at Trp¹³⁰ changed conformation of the catalytic active site, and faced Glu¹³¹ in the opposite direction toward its substrate, HA, indicating that C-mannosylation will negatively regulate its secretion, and will attenuate its enzymatic activity. Taken together, this is the first report that demonstrates the presence of C-mannosylation among HYAL family proteins, and our results suggest possible roles of C-mannosylation for secretion and enzymatic activity.

HighlightsHyaluronidase1 (HYAL1) is N-glycosylated at Asn99, Asn216, and Asn350.N-glycosylation regulates secretion of HYAL1.N-glycosylation is important for enzymatic activity of HYAL1.

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