Proteomic analysis of sea urchin (Strongylocentrotus purpuratus) spicule matrix

Table 1 Occurrence of SM proteins and other C-type lectin-like domain-containing proteins in sea urchin skeletal element proteomes

Protein	Database entry	Test ⁴	Spine ⁴	Tooth ⁵	Spicule
SM30-A	Glean3:00825	- [-]	- [-]	- [-]	- [++]
SM30-B/C ¹	Glean3:00826 Glean3:00827	- [+]	- [++]	- [+]	+ [++]
SM30-D ³	Glean3:00828 SPU:000828	+ [++]	++ [++]	++ [++]	- [-]
SM30-E	Glean3:04867	++ [++]	++ [+]	++ [++]	++ [+]
SM30-F	Glean3:04869	- [-]	+ [+]	- [+]	- [-]
Sp-Clect	Glean3:00164	-	(+)	+	++
SM50	Glean:18811	++	++	++	++
PM27 ³	Glean3:30147 UniProtKB:Q26616	++	++	++	++
SM29	Glean3:05990	++	++	++	++
Sp-Clect_14/similar to SM29	Glean3:05991	(+)	++	++	++
Sp-Adndatrnas/similar to SM29	Glean3:05992	+	-	+	-
SM32	Glean3:18810	++	++	++	++
SM37	Glean3:18813	++	++	++	++
Sp-Clect_13	Glean3:05989	++	++	++	++
Sp-Clect_25	Glean3:11163	++	++	(+)	++
Sp-C-lectin/ PMC1	Glean3:27906	+	+	+	+
Sp-Clect_76	Glean3:13825	++	+	++	++

⁺⁺among the 33% of most abundant proteins in the respective skeletal element; +, present; (+), tentatively identified; -, not identified. ¹, SM30-B and SM30-C are 97% identical, two identified peptides potentially occur in both proteins. ², it was noticed during the present data analysis that SpBase and Glean3 database contained different sequences for SM30-D; re-analysis confirmed the presence of SM30-D in adult tissues.³, the absence of the PM27 sequence in the Glean3 database was only noticed, and its sequence added, during data evaluation for the present report. The data for test, spine and tooth were obtained by re-analysis of the old raw-files with MaxQuant. ⁴, [25, 27]. ⁵, [26, 27]. Recent gene expression data for the SM30 family [derived from Figure 2 and Figure 5 of reference [44]] are shown in square brackets. The SM30 family of proteins is in bold print; the SM50 family of proteins is in italics.

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