Roborovskin, a Lipocalin in the Urine of the Roborovski Hamster, Phodopus roborovskii

Abstract

Many rodents are now known to exhibit an obligate proteinuria that delivers urine-mediated chemosignals. In this paper, we explore the urinary proteins of the Roborovski hamster (Phodopus roborovskii). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of urine from individual male and female Roborovski hamsters revealed 2 proteins, with approximate masses of 6 and 17 kDa, the expression pattern of which showed little variation between individuals or between sexes. Peptide mass fingerprints obtained from these 2 proteins revealed a number of features: 1) the proteins of a given mass were the same in all individuals regardless of sex, 2) the 6 kDa protein was not a fragment of the 21 kDa protein, and 3) neither protein was a fragment of a larger, conserved protein such as serum albumin. Electrospray mass spectrometry of purified protein preparations established the mass of the larger protein as invariant, at 17144 ± 2 Da in all samples. This protein has been termed roborovskin. The primary structure of roborovskin was determined by tandem mass spectrometry of peptides derived from independent and overlapping digestion with 3 proteases, supported by Edman degradation of the protein N-terminus. Roborovskin shared significant homology with olfactory-binding proteins from Myodes glareolus (bank vole) and with aphrodisin and submandibular protein from the golden hamster Mesocricetus auratus, all of which belong to the lipocalin superfamily. Lower levels of homology were also indicated between a variety of other lipocalins including the major urinary proteins from house mice and Norway rats. A model of the tertiary structure of roborovskin was constructed from the primary sequence by homology modeling. This model structure resembled other 8-stranded beta barrel lipocalins. Thus, the Roborovski hamster may demonstrate another variant of urinary lipocalin expression, as for the animals studied here, there appears to be no polymorphism in expression either between sexes or individuals.

Male-Specific Submaxillary Gland Protein, a Lipocalin Allergen of the Golden Hamster, Differs from the Lipocalin Allergens of Siberian and Roborovski Dwarf Hamsters

“…Our analysis of a 21-kDa IgE-reactive protein found in the fur and also abundantly in the SMG of the Roborovski hamster resulted in the identification of this allergen protein as roborovskin, which is a lipocalin, previously reported by Turton et al [11 ]in the urine of Roborovski hamsters of both sexes. Our 2D-gel electrophoresis analysis of this IgE-reactive 21-kDa lipocalin allergen showed that it is comprised of several isoforms, resolving as different spots at different acidic isoelectric points.…”

“…This N-terminal sequence was highly similar, but not identical to the sequence of roborovskin, a lipocalin protein earlier identified in the urine of Roborovski hamsters, the sequence of which was also determined by Edman degradation and mass spectrometry [11]. …”

“…The protein spots were subjected to Edman sequencing and mass spectrometry analysis. Translated cDNA (GI:530376029) of a Siberian hamster SMG lipocalin and the sequence of roborovskin, a lipocalin isolated from urine of Roborovski hamster [11] were used as references for the mass spectrometry analysis. Isobaric leucine (L) and isoleucine (I) amino acids cannot be distinguished by mass spectrometry and are indicated by J in the roborovskin and peptide sequences of IgE-reactive spots 3-5, except for in the N-terminal region where they were resolved by Edman degradation.…”

“…So far, no allergens have been described for the Golden or Roborovski hamsters. In the latter, a lipocalin called roborovskin has been identified in the urine [11], but its distribution in the body fur, its tissue of origin and whether it might be an allergen have not been investigated. In the Golden hamster, a male-specific submaxillary gland protein (MSP) has been identified, which is secreted in the saliva and excreted in the urine of males.…”

Oestrus cycle of the Desert hamster (Phodopus roborovskii, Satunin, 1903)

“…6,10,11 The aim of the present study was to characterize the oestrus cycle in the Desert hamster, Phodopus roborovskii, a species which is of interest for chronobiological studies, especially if associated with the sociobiological aspect as this species combines well-defined locomotor activity, 12 similar to the Golden hamster, with a social way of life and with intense paternal care. Besides studies concerning physiological adaptations to desert life, 13 this species has recently been used for the analysis of chemosignals, 14,15 obesity 16,17 and community structure in a changing environment. 18,19 Desert hamsters are the smallest hamsters of the Cricetinae family with a weight of 12-20 g and a body length of 6-8 cm.…”